Add more null annotations to automation bundles (#2763)

* Add more null annotations to automation bundles. This adds null annotations to many classes in the automation bundles and a few dimension classes.
* Further cleanup AutomationCommandExport
* Remove null from RuleStatusInfo JavaDocs. This should be clear from how the class is now annotated.
* Validate deserialized RuleStatusInfo
* Allow TriggerHandlerCallback to be triggered without providing a context

Signed-off-by: Wouter Born <github@maindrain.net>

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/internal/AbstractScriptedModuleHandlerFactory.java

@@ -12,6 +12,8 @@
  */
 package org.openhab.core.automation.module.script.rulesupport.internal;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Action;
 import org.openhab.core.automation.Condition;
 import org.openhab.core.automation.Module;
@@ -36,10 +38,11 @@ import org.slf4j.LoggerFactory;
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public abstract class AbstractScriptedModuleHandlerFactory extends BaseModuleHandlerFactory {
     Logger logger = LoggerFactory.getLogger(AbstractScriptedModuleHandlerFactory.class);
 
-    protected ModuleHandler getModuleHandler(Module module, ScriptedHandler scriptedHandler) {
+    protected @Nullable ModuleHandler getModuleHandler(Module module, @Nullable ScriptedHandler scriptedHandler) {
         ModuleHandler moduleHandler = null;
 
         if (scriptedHandler != null) {

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/internal/ScriptedCustomModuleHandlerFactory.java

@@ -15,6 +15,8 @@ package org.openhab.core.automation.module.script.rulesupport.internal;
 import java.util.Collection;
 import java.util.HashMap;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Module;
 import org.openhab.core.automation.handler.ModuleHandler;
 import org.openhab.core.automation.handler.ModuleHandlerFactory;
@@ -31,6 +33,7 @@ import org.osgi.service.component.annotations.Component;
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 @Component(immediate = true, service = { ScriptedCustomModuleHandlerFactory.class, ModuleHandlerFactory.class })
 public class ScriptedCustomModuleHandlerFactory extends AbstractScriptedModuleHandlerFactory {
     private final HashMap<String, ScriptedHandler> typesHandlers = new HashMap<>();
@@ -41,7 +44,7 @@ public class ScriptedCustomModuleHandlerFactory extends AbstractScriptedModuleHa
     }
 
     @Override
-    protected ModuleHandler internalCreate(Module module, String ruleUID) {
+    protected @Nullable ModuleHandler internalCreate(Module module, String ruleUID) {
         ScriptedHandler scriptedHandler = typesHandlers.get(module.getTypeUID());
 
         return getModuleHandler(module, scriptedHandler);

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/internal/ScriptedPrivateModuleHandlerFactory.java

@@ -16,6 +16,8 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashMap;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Module;
 import org.openhab.core.automation.handler.ModuleHandler;
 import org.openhab.core.automation.handler.ModuleHandlerFactory;
@@ -33,6 +35,7 @@ import org.slf4j.LoggerFactory;
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 @Component(immediate = true, service = { ScriptedPrivateModuleHandlerFactory.class, ModuleHandlerFactory.class })
 public class ScriptedPrivateModuleHandlerFactory extends AbstractScriptedModuleHandlerFactory {
     private static final String PRIV_ID = "privId";
@@ -50,7 +53,7 @@ public class ScriptedPrivateModuleHandlerFactory extends AbstractScriptedModuleH
     }
 
     @Override
-    protected ModuleHandler internalCreate(Module module, String ruleUID) {
+    protected @Nullable ModuleHandler internalCreate(Module module, String ruleUID) {
         ModuleHandler moduleHandler = null;
 
         ScriptedHandler scriptedHandler = null;

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/internal/delegates/SimpleActionHandlerDelegate.java

@@ -17,6 +17,8 @@ import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Action;
 import org.openhab.core.automation.handler.BaseActionModuleHandler;
 import org.openhab.core.automation.module.script.rulesupport.shared.simple.SimpleActionHandler;
@@ -26,6 +28,7 @@ import org.openhab.core.automation.module.script.rulesupport.shared.simple.Simpl
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public class SimpleActionHandlerDelegate extends BaseActionModuleHandler {
 
     private org.openhab.core.automation.module.script.rulesupport.shared.simple.SimpleActionHandler actionHandler;
@@ -41,10 +44,10 @@ public class SimpleActionHandlerDelegate extends BaseActionModuleHandler {
     }
 
     @Override
-    public Map<String, Object> execute(Map<String, Object> inputs) {
+    public @Nullable Map<String, Object> execute(Map<String, @Nullable Object> inputs) {
         Set<String> keys = new HashSet<>(inputs.keySet());
 
-        Map<String, Object> extendedInputs = new HashMap<>(inputs);
+        Map<String, @Nullable Object> extendedInputs = new HashMap<>(inputs);
         for (String key : keys) {
             Object value = extendedInputs.get(key);
             int dotIndex = key.indexOf('.');

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/internal/delegates/SimpleConditionHandlerDelegate.java

@@ -14,6 +14,7 @@ package org.openhab.core.automation.module.script.rulesupport.internal.delegates
 
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.Condition;
 import org.openhab.core.automation.handler.BaseConditionModuleHandler;
 import org.openhab.core.automation.module.script.rulesupport.shared.simple.SimpleConditionHandler;
@@ -23,6 +24,7 @@ import org.openhab.core.automation.module.script.rulesupport.shared.simple.Simpl
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public class SimpleConditionHandlerDelegate extends BaseConditionModuleHandler {
 
     private SimpleConditionHandler conditionHandler;

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/internal/delegates/SimpleTriggerHandlerCallbackDelegate.java

@@ -15,6 +15,8 @@ package org.openhab.core.automation.module.script.rulesupport.internal.delegates
 import java.util.Map;
 import java.util.concurrent.ScheduledExecutorService;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.RuleStatus;
 import org.openhab.core.automation.RuleStatusInfo;
 import org.openhab.core.automation.Trigger;
@@ -26,6 +28,7 @@ import org.openhab.core.automation.module.script.rulesupport.shared.simple.Simpl
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public class SimpleTriggerHandlerCallbackDelegate implements SimpleTriggerHandlerCallback {
     private final Trigger trigger;
     private final TriggerHandlerCallback callback;
@@ -51,7 +54,7 @@ public class SimpleTriggerHandlerCallbackDelegate implements SimpleTriggerHandle
     }
 
     @Override
-    public Boolean isEnabled(String ruleUID) {
+    public @Nullable Boolean isEnabled(String ruleUID) {
         return callback.isEnabled(ruleUID);
     }
 
@@ -61,12 +64,12 @@ public class SimpleTriggerHandlerCallbackDelegate implements SimpleTriggerHandle
     }
 
     @Override
-    public RuleStatusInfo getStatusInfo(String ruleUID) {
+    public @Nullable RuleStatusInfo getStatusInfo(String ruleUID) {
         return callback.getStatusInfo(ruleUID);
     }
 
     @Override
-    public RuleStatus getStatus(String ruleUID) {
+    public @Nullable RuleStatus getStatus(String ruleUID) {
         return callback.getStatus(ruleUID);
     }
 
@@ -76,7 +79,7 @@ public class SimpleTriggerHandlerCallbackDelegate implements SimpleTriggerHandle
     }
 
     @Override
-    public void runNow(String uid, boolean considerConditions, Map<String, Object> context) {
+    public void runNow(String uid, boolean considerConditions, @Nullable Map<String, Object> context) {
         callback.runNow(uid, considerConditions, context);
     }
 }

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/internal/delegates/SimpleTriggerHandlerDelegate.java

@@ -12,6 +12,7 @@
  */
 package org.openhab.core.automation.module.script.rulesupport.internal.delegates;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.ModuleHandlerCallback;
 import org.openhab.core.automation.Trigger;
 import org.openhab.core.automation.handler.BaseTriggerModuleHandler;
@@ -22,6 +23,7 @@ import org.openhab.core.automation.handler.TriggerHandlerCallback;
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public class SimpleTriggerHandlerDelegate extends BaseTriggerModuleHandler {
 
     private final org.openhab.core.automation.module.script.rulesupport.shared.simple.SimpleTriggerHandler triggerHandler;

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/internal/loader/ScriptLibraryWatcher.java

@@ -18,6 +18,8 @@ import java.io.File;
 import java.nio.file.Path;
 import java.nio.file.WatchEvent;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.service.AbstractWatchService;
 
 /**
@@ -25,6 +27,7 @@ import org.openhab.core.service.AbstractWatchService;
  *
  * @author Jonathan Gilbert - Initial contribution
  */
+@NonNullByDefault
 public abstract class ScriptLibraryWatcher extends AbstractWatchService {
 
     public ScriptLibraryWatcher(final String libraryPath) {
@@ -37,7 +40,7 @@ public abstract class ScriptLibraryWatcher extends AbstractWatchService {
     }
 
     @Override
-    protected WatchEvent.Kind<?>[] getWatchEventKinds(Path path) {
+    protected WatchEvent.Kind<?> @Nullable [] getWatchEventKinds(Path path) {
         return new WatchEvent.Kind<?>[] { ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY };
     }
 

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/internal/loader/collection/BidiSetBag.java

@@ -18,6 +18,8 @@ import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+
 /**
  * Bidirectional bag of unique elements. A map allowing multiple, unique values to be stored against a single key.
  * Provides optimized lookup of values for a key, as well as keys referencing a value.
@@ -26,6 +28,7 @@ import java.util.Set;
  * @param <K> Type of Key
  * @param <V> Type of Value
  */
+@NonNullByDefault
 public class BidiSetBag<K, V> {
     private Map<K, Set<V>> keyToValues = new HashMap<>();
     private Map<V, Set<K>> valueToKeys = new HashMap<>();

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/shared/ScriptedHandler.java

@@ -12,11 +12,14 @@
  */
 package org.openhab.core.automation.module.script.rulesupport.shared;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+
 /**
  * Empty interface to identify scripted handlers
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public interface ScriptedHandler {
 
 }

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/shared/factories/ScriptedActionHandlerFactory.java

@@ -12,6 +12,8 @@
  */
 package org.openhab.core.automation.module.script.rulesupport.shared.factories;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Action;
 import org.openhab.core.automation.handler.ActionHandler;
 import org.openhab.core.automation.module.script.rulesupport.shared.ScriptedHandler;
@@ -20,6 +22,7 @@ import org.openhab.core.automation.module.script.rulesupport.shared.ScriptedHand
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public interface ScriptedActionHandlerFactory extends ScriptedHandler {
-    public ActionHandler get(Action action);
+    public @Nullable ActionHandler get(Action action);
 }

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/shared/factories/ScriptedConditionHandlerFactory.java

@@ -12,6 +12,8 @@
  */
 package org.openhab.core.automation.module.script.rulesupport.shared.factories;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Condition;
 import org.openhab.core.automation.handler.ConditionHandler;
 import org.openhab.core.automation.module.script.rulesupport.shared.ScriptedHandler;
@@ -20,6 +22,7 @@ import org.openhab.core.automation.module.script.rulesupport.shared.ScriptedHand
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public interface ScriptedConditionHandlerFactory extends ScriptedHandler {
-    public ConditionHandler get(Condition module);
+    public @Nullable ConditionHandler get(Condition module);
 }

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/shared/factories/ScriptedTriggerHandlerFactory.java

@@ -12,6 +12,8 @@
  */
 package org.openhab.core.automation.module.script.rulesupport.shared.factories;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Trigger;
 import org.openhab.core.automation.handler.TriggerHandler;
 import org.openhab.core.automation.module.script.rulesupport.shared.ScriptedHandler;
@@ -20,6 +22,7 @@ import org.openhab.core.automation.module.script.rulesupport.shared.ScriptedHand
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public interface ScriptedTriggerHandlerFactory extends ScriptedHandler {
-    public TriggerHandler get(Trigger module);
+    public @Nullable TriggerHandler get(Trigger module);
 }

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/shared/simple/SimpleActionHandler.java

@@ -14,6 +14,7 @@ package org.openhab.core.automation.module.script.rulesupport.shared.simple;
 
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.Action;
 import org.openhab.core.automation.module.script.rulesupport.shared.ScriptedHandler;
 
@@ -21,6 +22,7 @@ import org.openhab.core.automation.module.script.rulesupport.shared.ScriptedHand
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public abstract class SimpleActionHandler implements ScriptedHandler {
     public void init(Action module) {
     }

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/shared/simple/SimpleConditionHandler.java

@@ -14,6 +14,7 @@ package org.openhab.core.automation.module.script.rulesupport.shared.simple;
 
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.Condition;
 import org.openhab.core.automation.module.script.rulesupport.shared.ScriptedHandler;
 
@@ -21,6 +22,7 @@ import org.openhab.core.automation.module.script.rulesupport.shared.ScriptedHand
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public abstract class SimpleConditionHandler implements ScriptedHandler {
     public void init(Condition condition) {
     }

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/shared/simple/SimpleRuleActionHandler.java

@@ -14,12 +14,14 @@ package org.openhab.core.automation.module.script.rulesupport.shared.simple;
 
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.Action;
 
 /**
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public interface SimpleRuleActionHandler {
     Object execute(Action module, Map<String, ?> inputs);
 }

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/shared/simple/SimpleRuleActionHandlerDelegate.java

@@ -14,12 +14,14 @@ package org.openhab.core.automation.module.script.rulesupport.shared.simple;
 
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.Action;
 
 /**
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public class SimpleRuleActionHandlerDelegate extends SimpleActionHandler {
 
     private SimpleRuleActionHandler handler;

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/shared/simple/SimpleTriggerHandler.java

@@ -14,6 +14,8 @@ package org.openhab.core.automation.module.script.rulesupport.shared.simple;
 
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Trigger;
 import org.openhab.core.automation.module.script.rulesupport.shared.ScriptedHandler;
 
@@ -21,8 +23,9 @@ import org.openhab.core.automation.module.script.rulesupport.shared.ScriptedHand
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public abstract class SimpleTriggerHandler implements ScriptedHandler {
-    private SimpleTriggerHandlerCallback ruleCallback;
+    private @Nullable SimpleTriggerHandlerCallback ruleCallback;
 
     public void init(Trigger module) {
     }
@@ -32,6 +35,9 @@ public abstract class SimpleTriggerHandler implements ScriptedHandler {
     }
 
     protected void trigger(Map<String, ?> context) {
-        this.ruleCallback.triggered(context);
+        SimpleTriggerHandlerCallback callback = this.ruleCallback;
+        if (callback != null) {
+            callback.triggered(context);
+        }
     }
 }

bundles/org.openhab.core.automation.module.script.rulesupport/src/main/java/org/openhab/core/automation/module/script/rulesupport/shared/simple/SimpleTriggerHandlerCallback.java

@@ -14,12 +14,14 @@ package org.openhab.core.automation.module.script.rulesupport.shared.simple;
 
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.handler.TriggerHandlerCallback;
 
 /**
  *
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public interface SimpleTriggerHandlerCallback extends TriggerHandlerCallback {
     public void triggered(Map<String, ?> context);
 }

bundles/org.openhab.core.automation.module.script/src/main/java/org/openhab/core/automation/module/script/internal/defaultscope/ItemRegistryDelegate.java

@@ -17,6 +17,7 @@ import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.items.Item;
 import org.openhab.core.items.ItemNotFoundException;
@@ -28,6 +29,7 @@ import org.openhab.core.types.State;
  *
  * @author Kai Kreuzer - Initial contribution
  */
+@NonNullByDefault
 public class ItemRegistryDelegate implements Map<String, State> {
 
     private final ItemRegistry itemRegistry;
@@ -47,10 +49,11 @@ public class ItemRegistryDelegate implements Map<String, State> {
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@Nullable Object key) {
         if (key instanceof String) {
             try {
-                return itemRegistry.getItem((String) key) != null;
+                itemRegistry.getItem((String) key);
+                return true;
             } catch (ItemNotFoundException e) {
                 return false;
             }
@@ -60,12 +63,12 @@ public class ItemRegistryDelegate implements Map<String, State> {
     }
 
     @Override
-    public boolean containsValue(Object value) {
+    public boolean containsValue(@Nullable Object value) {
         return false;
     }
 
     @Override
-    public State get(@Nullable Object key) {
+    public @Nullable State get(@Nullable Object key) {
         if (key == null) {
             return null;
         }
@@ -77,12 +80,12 @@ public class ItemRegistryDelegate implements Map<String, State> {
     }
 
     @Override
-    public State put(String key, State value) {
+    public @Nullable State put(String key, State value) {
         throw new UnsupportedOperationException();
     }
 
     @Override
-    public State remove(Object key) {
+    public @Nullable State remove(@Nullable Object key) {
         throw new UnsupportedOperationException();
     }
 

bundles/org.openhab.core.automation.rest/src/main/java/org/openhab/core/automation/rest/internal/dto/EnrichedRuleDTOMapper.java

@@ -12,6 +12,7 @@
  */
 package org.openhab.core.automation.rest.internal.dto;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.ManagedRuleProvider;
 import org.openhab.core.automation.Rule;
 import org.openhab.core.automation.RuleManager;
@@ -23,6 +24,7 @@ import org.openhab.core.automation.dto.RuleDTOMapper;
  * @author Markus Rathgeb - Initial contribution
  * @author Kai Kreuzer - added editable field
  */
+@NonNullByDefault
 public class EnrichedRuleDTOMapper extends RuleDTOMapper {
 
     public static EnrichedRuleDTO map(final Rule rule, final RuleManager ruleEngine,

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/RulePredicates.java

@@ -19,11 +19,15 @@ import java.util.HashSet;
 import java.util.Set;
 import java.util.function.Predicate;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+
 /**
  * This class add support for prefixes for {@link Rule} UIDs and provide default predicates for prefixes and tags.
  *
  * @author Victor Toni - Initial contribution
  */
+@NonNullByDefault
 public class RulePredicates {
 
     /**
@@ -48,7 +52,7 @@ public class RulePredicates {
      *
      * @return prefix of this {@link Rule}, or {@code null} if no prefix or an empty prefix is found.
      */
-    public static String getPrefix(Rule rule) {
+    public static @Nullable String getPrefix(@Nullable Rule rule) {
         if (null != rule) {
             final String uid = rule.getUID();
             final int index = uid.indexOf(PREFIX_SEPARATOR);
@@ -66,7 +70,7 @@ public class RulePredicates {
      * @param prefix to search for.
      * @return created {@link Predicate}.
      */
-    public static Predicate<Rule> hasPrefix(final String prefix) {
+    public static Predicate<Rule> hasPrefix(final @Nullable String prefix) {
         if (null == prefix) {
             return r -> null == getPrefix(r);
         } else {
@@ -121,7 +125,7 @@ public class RulePredicates {
      * @param tags to search for.
      * @return created {@link Predicate}.
      */
-    public static Predicate<Rule> hasAllTags(final Collection<String> tags) {
+    public static Predicate<Rule> hasAllTags(final @Nullable Collection<String> tags) {
         if (tags == null || tags.isEmpty()) {
             return (Predicate<Rule>) r -> true;
         } else {
@@ -140,7 +144,7 @@ public class RulePredicates {
      * @param tags to search for.
      * @return created {@link Predicate}.
      */
-    public static Predicate<Rule> hasAllTags(final String... tags) {
+    public static Predicate<Rule> hasAllTags(final String @Nullable... tags) {
         return hasAllTags(tags == null ? null : Arrays.asList(tags));
     }
 
@@ -151,7 +155,7 @@ public class RulePredicates {
      * @param tags to search for.
      * @return created {@link Predicate}.
      */
-    public static Predicate<Rule> hasAnyOfTags(final Collection<String> tags) {
+    public static Predicate<Rule> hasAnyOfTags(final @Nullable Collection<String> tags) {
         if (null == tags || tags.isEmpty()) {
             // everything without a tag is matching
             return hasNoTags();
@@ -171,7 +175,7 @@ public class RulePredicates {
      * @param tags to search for.
      * @return created {@link Predicate}.
      */
-    public static Predicate<Rule> hasAnyOfTags(final String... tags) {
+    public static Predicate<Rule> hasAnyOfTags(final String @Nullable... tags) {
         if (null == tags || 0 == tags.length) {
             // everything without a tag is matching
             return hasNoTags();

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/RuleStatusInfo.java

@@ -12,6 +12,9 @@
  */
 package org.openhab.core.automation;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+
 /**
  * This class is used to present status of a rule. The status consists of three parts:
  * The main status, a status detail and a string description.
@@ -19,11 +22,12 @@ package org.openhab.core.automation;
  * @author Yordan Mihaylov - Initial contribution
  * @author Kai Kreuzer - Refactored to match ThingStatusInfo implementation
  */
+@NonNullByDefault
 public class RuleStatusInfo {
 
-    private RuleStatus status;
+    private @NonNullByDefault({}) RuleStatus status;
-    private RuleStatusDetail statusDetail;
+    private @NonNullByDefault({}) RuleStatusDetail statusDetail;
-    private String description;
+    private @Nullable String description;
 
     /**
      * Default constructor for deserialization e.g. by Gson.
@@ -34,40 +38,30 @@ public class RuleStatusInfo {
     /**
      * Constructs a status info.
      *
-     * @param status the status (must not be null)
+     * @param status the status
-     * @throws IllegalArgumentException if status is null
      */
-    public RuleStatusInfo(RuleStatus status) throws IllegalArgumentException {
+    public RuleStatusInfo(RuleStatus status) {
         this(status, RuleStatusDetail.NONE);
     }
 
     /**
      * Constructs a status info.
      *
-     * @param status the status (must not be null)
+     * @param status the status
-     * @param statusDetail the detail of the status (must not be null)
+     * @param statusDetail the detail of the status
-     * @throws IllegalArgumentException if status or status detail is null
      */
-    public RuleStatusInfo(RuleStatus status, RuleStatusDetail statusDetail) throws IllegalArgumentException {
+    public RuleStatusInfo(RuleStatus status, RuleStatusDetail statusDetail) {
         this(status, statusDetail, null);
     }
 
     /**
      * Constructs a status info.
      *
-     * @param status the status (must not be null)
+     * @param status the status
-     * @param statusDetail the detail of the status (must not be null)
+     * @param statusDetail the detail of the status
      * @param description the description of the status
-     * @throws IllegalArgumentException if status or status detail is null
      */
-    public RuleStatusInfo(RuleStatus status, RuleStatusDetail statusDetail, String description)
+    public RuleStatusInfo(RuleStatus status, RuleStatusDetail statusDetail, @Nullable String description) {
-            throws IllegalArgumentException {
-        if (status == null) {
-            throw new IllegalArgumentException("Thing status must not be null");
-        }
-        if (statusDetail == null) {
-            throw new IllegalArgumentException("Thing status detail must not be null");
-        }
         this.status = status;
         this.statusDetail = statusDetail;
         this.description = description;
@@ -76,7 +70,7 @@ public class RuleStatusInfo {
     /**
      * Gets the status itself.
      *
-     * @return the status (not null)
+     * @return the status
      */
     public RuleStatus getStatus() {
         return status;
@@ -85,7 +79,7 @@ public class RuleStatusInfo {
     /**
      * Gets the detail of the status.
      *
-     * @return the status detail (not null)
+     * @return the status detail
      */
     public RuleStatusDetail getStatusDetail() {
         return statusDetail;
@@ -96,7 +90,7 @@ public class RuleStatusInfo {
      *
      * @return the description
      */
-    public String getDescription() {
+    public @Nullable String getDescription() {
         return description;
     }
 
@@ -118,7 +112,7 @@ public class RuleStatusInfo {
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@Nullable Object obj) {
         if (this == obj) {
             return true;
         }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/StatusInfoCallback.java

@@ -1,29 +0,0 @@
-/**
- * Copyright (c) 2010-2022 Contributors to the openHAB project
- *
- * See the NOTICE file(s) distributed with this work for additional
- * information.
- *
- * This program and the accompanying materials are made available under the
- * terms of the Eclipse Public License 2.0 which is available at
- * http://www.eclipse.org/legal/epl-2.0
- *
- * SPDX-License-Identifier: EPL-2.0
- */
-package org.openhab.core.automation;
-
-/**
- * This interface is used by {@link RuleRegistry} implementation to be notified of changes related to statuses of rules.
- *
- * @author Yordan Mihaylov - Initial contribution
- */
-public interface StatusInfoCallback {
-
-    /**
-     * The method is called when the rule has update of its status.
-     *
-     * @param ruleUID UID of the {@link Rule}
-     * @param statusInfo new status info releated to the {@link Rule}
-     */
-    void statusInfoChanged(String ruleUID, RuleStatusInfo statusInfo);
-}

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/dto/ActionDTOMapper.java

@@ -16,6 +16,8 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Action;
 import org.openhab.core.automation.util.ModuleBuilder;
 import org.openhab.core.config.core.Configuration;
@@ -26,6 +28,7 @@ import org.openhab.core.config.core.Configuration;
  * @author Markus Rathgeb - Initial contribution
  * @author Kai Kreuzer - Changed to using ModuleBuilder
  */
+@NonNullByDefault
 public class ActionDTOMapper extends ModuleDTOMapper {
 
     public static ActionDTO map(final Action action) {
@@ -41,9 +44,9 @@ public class ActionDTOMapper extends ModuleDTOMapper {
                 .withLabel(actionDto.label).withDescription(actionDto.description).build();
     }
 
-    public static List<ActionDTO> map(final Collection<? extends Action> actions) {
+    public static List<ActionDTO> map(final @Nullable Collection<? extends Action> actions) {
         if (actions == null) {
-            return null;
+            return List.of();
         }
         final List<ActionDTO> dtos = new ArrayList<>(actions.size());
         for (final Action action : actions) {
@@ -52,9 +55,9 @@ public class ActionDTOMapper extends ModuleDTOMapper {
         return dtos;
     }
 
-    public static List<Action> mapDto(final Collection<ActionDTO> dtos) {
+    public static List<Action> mapDto(final @Nullable Collection<ActionDTO> dtos) {
         if (dtos == null) {
-            return null;
+            return List.of();
         }
         final List<Action> actions = new ArrayList<>(dtos.size());
         for (final ActionDTO dto : dtos) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/dto/ActionTypeDTOMapper.java

@@ -16,6 +16,8 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.type.ActionType;
 import org.openhab.core.automation.type.CompositeActionType;
 import org.openhab.core.config.core.dto.ConfigDescriptionDTOMapper;
@@ -26,6 +28,7 @@ import org.openhab.core.config.core.dto.ConfigDescriptionDTOMapper;
  * @author Markus Rathgeb - Initial contribution
  * @author Ana Dimova - extends Action Module type DTOs with composites
  */
+@NonNullByDefault
 public class ActionTypeDTOMapper extends ModuleTypeDTOMapper {
 
     public static ActionTypeDTO map(final ActionType actionType) {
@@ -51,9 +54,9 @@ public class ActionTypeDTOMapper extends ModuleTypeDTOMapper {
         }
     }
 
-    public static List<ActionTypeDTO> map(final Collection<ActionType> types) {
+    public static List<ActionTypeDTO> map(final @Nullable Collection<ActionType> types) {
         if (types == null) {
-            return null;
+            return List.of();
         }
         final List<ActionTypeDTO> dtos = new ArrayList<>(types.size());
         for (final ActionType type : types) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/dto/ConditionDTOMapper.java

@@ -15,6 +15,8 @@ package org.openhab.core.automation.dto;
 import java.util.ArrayList;
 import java.util.List;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Condition;
 import org.openhab.core.automation.util.ModuleBuilder;
 import org.openhab.core.config.core.Configuration;
@@ -25,6 +27,7 @@ import org.openhab.core.config.core.Configuration;
  * @author Markus Rathgeb - Initial contribution
  * @author Kai Kreuzer - Changed to using ModuleBuilder
  */
+@NonNullByDefault
 public class ConditionDTOMapper extends ModuleDTOMapper {
 
     public static ConditionDTO map(final Condition condition) {
@@ -40,9 +43,9 @@ public class ConditionDTOMapper extends ModuleDTOMapper {
                 .withLabel(conditionDto.label).withDescription(conditionDto.description).build();
     }
 
-    public static List<ConditionDTO> map(final List<? extends Condition> conditions) {
+    public static List<ConditionDTO> map(final @Nullable List<? extends Condition> conditions) {
         if (conditions == null) {
-            return null;
+            return List.of();
         }
         final List<ConditionDTO> dtos = new ArrayList<>(conditions.size());
         for (final Condition action : conditions) {
@@ -51,9 +54,9 @@ public class ConditionDTOMapper extends ModuleDTOMapper {
         return dtos;
     }
 
-    public static List<Condition> mapDto(final List<ConditionDTO> dtos) {
+    public static List<Condition> mapDto(final @Nullable List<ConditionDTO> dtos) {
         if (dtos == null) {
-            return null;
+            return List.of();
         }
         final List<Condition> conditions = new ArrayList<>(dtos.size());
         for (final ConditionDTO dto : dtos) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/dto/ConditionTypeDTOMapper.java

@@ -16,6 +16,8 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.type.CompositeConditionType;
 import org.openhab.core.automation.type.ConditionType;
 import org.openhab.core.config.core.dto.ConfigDescriptionDTOMapper;
@@ -26,6 +28,7 @@ import org.openhab.core.config.core.dto.ConfigDescriptionDTOMapper;
  * @author Markus Rathgeb - Initial contribution
  * @author Ana Dimova - extends Condition Module type DTOs with composites
  */
+@NonNullByDefault
 public class ConditionTypeDTOMapper extends ModuleTypeDTOMapper {
 
     public static ConditionTypeDTO map(final ConditionType conditionType) {
@@ -52,9 +55,9 @@ public class ConditionTypeDTOMapper extends ModuleTypeDTOMapper {
         }
     }
 
-    public static List<ConditionTypeDTO> map(final Collection<ConditionType> types) {
+    public static List<ConditionTypeDTO> map(final @Nullable Collection<ConditionType> types) {
         if (types == null) {
-            return null;
+            return List.of();
         }
         final List<ConditionTypeDTO> dtos = new ArrayList<>(types.size());
         for (final ConditionType type : types) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/dto/ModuleDTOMapper.java

@@ -12,6 +12,7 @@
  */
 package org.openhab.core.automation.dto;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.Module;
 
 /**
@@ -19,6 +20,7 @@ import org.openhab.core.automation.Module;
  *
  * @author Markus Rathgeb - Initial contribution
  */
+@NonNullByDefault
 public class ModuleDTOMapper {
 
     protected static void fillProperties(final Module from, final ModuleDTO to) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/dto/ModuleTypeDTOMapper.java

@@ -12,6 +12,7 @@
  */
 package org.openhab.core.automation.dto;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.type.ModuleType;
 import org.openhab.core.config.core.dto.ConfigDescriptionDTOMapper;
 
@@ -20,6 +21,7 @@ import org.openhab.core.config.core.dto.ConfigDescriptionDTOMapper;
  *
  * @author Markus Rathgeb - Initial contribution
  */
+@NonNullByDefault
 public class ModuleTypeDTOMapper {
 
     protected static void fillProperties(final ModuleType from, final ModuleTypeDTO to) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/dto/RuleDTOMapper.java

@@ -12,6 +12,7 @@
  */
 package org.openhab.core.automation.dto;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.Rule;
 import org.openhab.core.automation.util.RuleBuilder;
 import org.openhab.core.config.core.Configuration;
@@ -23,6 +24,7 @@ import org.openhab.core.config.core.dto.ConfigDescriptionDTOMapper;
  * @author Markus Rathgeb - Initial contribution
  * @author Kai Kreuzer - Changed to using RuleBuilder
  */
+@NonNullByDefault
 public class RuleDTOMapper {
 
     public static RuleDTO map(final Rule rule) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/dto/TriggerDTOMapper.java

@@ -16,6 +16,8 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Trigger;
 import org.openhab.core.automation.util.ModuleBuilder;
 import org.openhab.core.config.core.Configuration;
@@ -26,6 +28,7 @@ import org.openhab.core.config.core.Configuration;
  * @author Markus Rathgeb - Initial contribution
  * @author Kai Kreuzer - Changed to using ModuleBuilder
  */
+@NonNullByDefault
 public class TriggerDTOMapper extends ModuleDTOMapper {
 
     public static TriggerDTO map(final Trigger trigger) {
@@ -40,9 +43,9 @@ public class TriggerDTOMapper extends ModuleDTOMapper {
                 .withDescription(triggerDto.description).build();
     }
 
-    public static List<TriggerDTO> map(final Collection<? extends Trigger> triggers) {
+    public static List<TriggerDTO> map(final @Nullable Collection<? extends Trigger> triggers) {
         if (triggers == null) {
-            return null;
+            return List.of();
         }
         final List<TriggerDTO> dtos = new ArrayList<>(triggers.size());
         for (final Trigger trigger : triggers) {
@@ -51,9 +54,9 @@ public class TriggerDTOMapper extends ModuleDTOMapper {
         return dtos;
     }
 
-    public static List<Trigger> mapDto(final Collection<TriggerDTO> dtos) {
+    public static List<Trigger> mapDto(final @Nullable Collection<TriggerDTO> dtos) {
         if (dtos == null) {
-            return null;
+            return List.of();
         }
         final List<Trigger> triggers = new ArrayList<>(dtos.size());
         for (final TriggerDTO dto : dtos) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/dto/TriggerTypeDTOMapper.java

@@ -16,6 +16,8 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.type.CompositeTriggerType;
 import org.openhab.core.automation.type.TriggerType;
 import org.openhab.core.config.core.dto.ConfigDescriptionDTOMapper;
@@ -26,6 +28,7 @@ import org.openhab.core.config.core.dto.ConfigDescriptionDTOMapper;
  * @author Markus Rathgeb - Initial contribution
  * @author Ana Dimova - extends Trigger Module type DTOs with composites
  */
+@NonNullByDefault
 public class TriggerTypeDTOMapper extends ModuleTypeDTOMapper {
 
     public static TriggerTypeDTO map(final TriggerType triggerType) {
@@ -51,9 +54,9 @@ public class TriggerTypeDTOMapper extends ModuleTypeDTOMapper {
         }
     }
 
-    public static List<TriggerTypeDTO> map(final Collection<TriggerType> types) {
+    public static List<TriggerTypeDTO> map(final @Nullable Collection<TriggerType> types) {
         if (types == null) {
-            return null;
+            return List.of();
         }
         final List<TriggerTypeDTO> dtos = new ArrayList<>(types.size());
         for (final TriggerType type : types) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/handler/BaseModuleHandlerFactory.java

@@ -74,7 +74,7 @@ public abstract class BaseModuleHandlerFactory implements ModuleHandlerFactory {
      *
      * @param module the {@link Module} for which a handler should be created.
      * @param ruleUID the identifier of the {@link Rule} that the given module belongs to.
-     * @return a {@link ModuleHandler} instance or {@code null} if thins module type is not supported.
+     * @return a {@link ModuleHandler} instance or {@code null} if this module type is not supported.
      */
     protected abstract @Nullable ModuleHandler internalCreate(Module module, String ruleUID);
 

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/handler/TriggerHandlerCallback.java

@@ -16,7 +16,6 @@ import java.util.Map;
 import java.util.concurrent.ScheduledExecutorService;
 
 import org.eclipse.jdt.annotation.NonNullByDefault;
-import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.ModuleHandlerCallback;
 import org.openhab.core.automation.Rule;
 import org.openhab.core.automation.Trigger;
@@ -37,7 +36,19 @@ public interface TriggerHandlerCallback extends ModuleHandlerCallback {
 
     /**
      * This method is used by the {@link TriggerHandler} to notify the RuleManager when
-     * the liked {@link Trigger} instance was fired.
+     * the linked {@link Trigger} instance was fired.
+     *
+     * @param trigger instance of trigger which was fired. When one TriggerHandler
+     *            serve more then one {@link Trigger} instances, this parameter
+     *            defines which trigger was fired.
+     */
+    default void triggered(Trigger trigger) {
+        triggered(trigger, Map.of());
+    }
+
+    /**
+     * This method is used by the {@link TriggerHandler} to notify the RuleManager when
+     * the linked {@link Trigger} instance was fired.
      *
      * @param trigger instance of trigger which was fired. When one TriggerHandler
      *            serve more then one {@link Trigger} instances, this parameter
@@ -49,10 +60,10 @@ public interface TriggerHandlerCallback extends ModuleHandlerCallback {
      *            <li><code>value</code> - represents output value of the {@link Trigger}'s {@link Output}
      *            </ul>
      */
-    public void triggered(Trigger trigger, @Nullable Map<String, ?> context);
+    void triggered(Trigger trigger, Map<String, ?> context);
 
     /**
      * @return the scheduler of this rule
      */
-    public ScheduledExecutorService getScheduler();
+    ScheduledExecutorService getScheduler();
 }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/RuleEngineImpl.java

@@ -662,7 +662,7 @@ public class RuleEngineImpl implements RuleManager, RegistryChangeListener<Modul
      * @param msg provides the {@link RuleStatusInfo} description, corresponding to the new <b>uninitialized</b>
      *            status, should be {@code null} if the status will be skipped.
      */
-    private void unregister(@Nullable WrappedRule r, @Nullable RuleStatusDetail detail, @Nullable String msg) {
+    private void unregister(@Nullable WrappedRule r, RuleStatusDetail detail, @Nullable String msg) {
         if (r != null) {
             unregister(r);
             setStatus(r.getUID(), new RuleStatusInfo(RuleStatus.UNINITIALIZED, detail, msg));

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/RuleEventFactory.java

@@ -91,8 +91,12 @@ public class RuleEventFactory extends AbstractEventFactory {
         return new RuleUpdatedEvent(topic, payload, source, ruleDTO[0], ruleDTO[1]);
     }
 
+    @SuppressWarnings("null")
     private Event createRuleStatusInfoEvent(String topic, String payload, @Nullable String source) {
         RuleStatusInfo statusInfo = deserializePayload(payload, RuleStatusInfo.class);
+        if (statusInfo.getStatus() == null || statusInfo.getStatusDetail() == null) {
+            throw new IllegalArgumentException("Creation of RuleStatusInfo failed: invalid payload: " + payload);
+        }
         return new RuleStatusInfoEvent(topic, payload, source, statusInfo, getRuleId(topic));
     }
 

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/TriggerHandlerCallbackImpl.java

@@ -54,7 +54,7 @@ public class TriggerHandlerCallbackImpl implements TriggerHandlerCallback {
     }
 
     @Override
-    public void triggered(Trigger trigger, @Nullable Map<String, ?> context) {
+    public void triggered(Trigger trigger, Map<String, ?> context) {
         synchronized (this) {
             future = executor.submit(new TriggerData(trigger, context));
         }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/commands/AutomationCommandEnableRule.java

@@ -12,6 +12,8 @@
  */
 package org.openhab.core.automation.internal.commands;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.RuleStatus;
 
 /**
@@ -19,6 +21,7 @@ import org.openhab.core.automation.RuleStatus;
  *
  * @author Ana Dimova - Initial contribution
  */
+@NonNullByDefault
 public class AutomationCommandEnableRule extends AutomationCommand {
 
     /**
@@ -34,7 +37,7 @@ public class AutomationCommandEnableRule extends AutomationCommand {
     /**
      * This field keeps the specified rule UID.
      */
-    private String uid;
+    private @Nullable String uid;
 
     public AutomationCommandEnableRule(String command, String[] parameterValues, int providerType,
             AutomationCommandsPluggable autoCommands) {
@@ -43,9 +46,11 @@ public class AutomationCommandEnableRule extends AutomationCommand {
 
     @Override
     public String execute() {
-        if (parsingResult != SUCCESS) {
+        String uid = this.uid;
+        if (!SUCCESS.equals(parsingResult) || uid == null) {
             return parsingResult;
         }
+
         if (hasEnable) {
             autoCommands.setEnabled(uid, enable);
             return SUCCESS;

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/commands/AutomationCommandExport.java

@@ -13,11 +13,12 @@
 package org.openhab.core.automation.internal.commands;
 
 import java.io.File;
-import java.util.Collection;
 import java.util.HashSet;
 import java.util.Locale;
 import java.util.Set;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.parser.Parser;
 
 /**
@@ -30,6 +31,7 @@ import org.openhab.core.automation.parser.Parser;
  *
  * @author Ana Dimova - Initial contribution
  */
+@NonNullByDefault
 public class AutomationCommandExport extends AutomationCommand {
 
     /**
@@ -47,7 +49,7 @@ public class AutomationCommandExport extends AutomationCommand {
     /**
      * This field keeps the path of the output file where the automation objects to be exported.
      */
-    private File file;
+    private @Nullable File file;
 
     /**
      * This field stores the value of <b>locale</b> parameter of the command.
@@ -75,46 +77,31 @@ public class AutomationCommandExport extends AutomationCommand {
     @SuppressWarnings("unchecked")
     @Override
     public String execute() {
-        if (parsingResult != SUCCESS) {
+        File file = this.file;
+        if (!SUCCESS.equals(parsingResult) || file == null) {
             return parsingResult;
         }
         @SuppressWarnings("rawtypes")
         Set set = new HashSet();
         switch (providerType) {
             case AutomationCommands.MODULE_TYPE_PROVIDER:
-                @SuppressWarnings("rawtypes")
+                set.addAll(autoCommands.getTriggers(locale));
-                Collection collection = autoCommands.getTriggers(locale);
+                set.addAll(autoCommands.getConditions(locale));
-                if (collection != null) {
+                set.addAll(autoCommands.getActions(locale));
-                    set.addAll(collection);
-                }
-                collection = autoCommands.getConditions(locale);
-                if (collection != null) {
-                    set.addAll(collection);
-                }
-                collection = autoCommands.getActions(locale);
-                if (collection != null) {
-                    set.addAll(collection);
-                }
                 try {
                     return autoCommands.exportModuleTypes(parserType, set, file);
                 } catch (Exception e) {
                     return getStackTrace(e);
                 }
             case AutomationCommands.TEMPLATE_PROVIDER:
-                collection = autoCommands.getTemplates(locale);
+                set.addAll(autoCommands.getTemplates(locale));
-                if (collection != null) {
-                    set.addAll(collection);
-                }
                 try {
                     return autoCommands.exportTemplates(parserType, set, file);
                 } catch (Exception e) {
                     return getStackTrace(e);
                 }
             case AutomationCommands.RULE_PROVIDER:
-                collection = autoCommands.getRules();
+                set.addAll(autoCommands.getRules());
-                if (collection != null) {
-                    set.addAll(collection);
-                }
                 try {
                     return autoCommands.exportRules(parserType, set, file);
                 } catch (Exception e) {
@@ -132,7 +119,7 @@ public class AutomationCommandExport extends AutomationCommand {
      * @return a {@link File} object created from the string that is passed as a parameter of the command or <b>null</b>
      *         if the parent directory could not be found or created or the string could not be parsed.
      */
-    private File initFile(String parameterValue) {
+    private @Nullable File initFile(String parameterValue) {
         File f = new File(parameterValue);
         File parent = f.getParentFile();
         return (parent == null || (!parent.isDirectory() && !parent.mkdirs())) ? null : f;
@@ -174,7 +161,8 @@ public class AutomationCommandExport extends AutomationCommand {
             } else if (parameterValues[i].charAt(0) == '-') {
                 return String.format("Unsupported option: %s", parameterValues[i]);
             } else if (getFile) {
-                file = initFile(parameterValues[i]);
+                File file = initFile(parameterValues[i]);
+                this.file = file;
                 if (file != null) {
                     getFile = false;
                 }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/commands/AutomationCommandImport.java

@@ -16,6 +16,8 @@ import java.io.File;
 import java.net.MalformedURLException;
 import java.net.URL;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.parser.Parser;
 
 /**
@@ -28,6 +30,7 @@ import org.openhab.core.automation.parser.Parser;
  *
  * @author Ana Dimova - Initial contribution
  */
+@NonNullByDefault
 public class AutomationCommandImport extends AutomationCommand {
 
     /**
@@ -45,7 +48,7 @@ public class AutomationCommandImport extends AutomationCommand {
     /**
      * This field keeps URL of the source of automation objects that has to be imported.
      */
-    private URL url;
+    private @Nullable URL url;
 
     /**
      * @see AutomationCommand#AutomationCommand(String, String[], int, AutomationCommandsPluggable)
@@ -65,7 +68,8 @@ public class AutomationCommandImport extends AutomationCommand {
      */
     @Override
     public String execute() {
-        if (parsingResult != SUCCESS) {
+        URL url = this.url;
+        if (!SUCCESS.equals(parsingResult) || url == null) {
             return parsingResult;
         }
         try {
@@ -95,7 +99,7 @@ public class AutomationCommandImport extends AutomationCommand {
      * @return an {@link URL} object created from the string that is passed as parameter of the command or <b>null</b>
      *         if either no legal protocol could be found in the specified string or the string could not be parsed.
      */
-    private URL initURL(String parameterValue) {
+    private @Nullable URL initURL(String parameterValue) {
         try {
             return new URL(parameterValue);
         } catch (MalformedURLException mue) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/commands/AutomationCommandRemove.java

@@ -16,6 +16,8 @@ import java.io.File;
 import java.net.MalformedURLException;
 import java.net.URL;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Rule;
 
 /**
@@ -31,17 +33,18 @@ import org.openhab.core.automation.Rule;
  * @author Kai Kreuzer - fixed feedback when deleting non-existent rule
  * @author Marin Mitev - removed prefixes in the output
  */
+@NonNullByDefault
 public class AutomationCommandRemove extends AutomationCommand {
 
     /**
      * This field keeps the UID of the {@link Rule} if command is {@link AutomationCommands#REMOVE_RULE}
      */
-    private String id;
+    private @Nullable String id;
 
     /**
      * This field keeps URL of the source of automation objects that has to be removed.
      */
-    private URL url;
+    private @Nullable URL url;
 
     /**
      * @see AutomationCommand#AutomationCommand(String, String[], int, AutomationCommandsPluggable)
@@ -62,7 +65,9 @@ public class AutomationCommandRemove extends AutomationCommand {
      */
     @Override
     public String execute() {
-        if (parsingResult != SUCCESS) {
+        String id = this.id;
+        URL url = this.url;
+        if (!SUCCESS.equals(parsingResult) || id == null || url == null) {
             return parsingResult;
         }
         switch (providerType) {
@@ -89,7 +94,7 @@ public class AutomationCommandRemove extends AutomationCommand {
      * @return an {@link URL} object created from the string that is passed as parameter of the command or <b>null</b>
      *         if either no legal protocol could be found in the specified string or the string could not be parsed.
      */
-    private URL initURL(String parameterValue) {
+    private @Nullable URL initURL(String parameterValue) {
         try {
             return new URL(parameterValue);
         } catch (MalformedURLException mue) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/commands/Utils.java

@@ -18,11 +18,14 @@ import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+
 /**
  * This class contains methods for facilitating sorting and filtering lists stored in {@link Hashtable}s.
  *
  * @author Ana Dimova - Initial contribution
  */
+@NonNullByDefault
 public class Utils {
 
     /**

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/composite/AbstractCompositeModuleHandler.java

@@ -17,6 +17,8 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Action;
 import org.openhab.core.automation.Condition;
 import org.openhab.core.automation.Module;
@@ -48,10 +50,11 @@ import org.openhab.core.automation.util.ReferenceResolver;
  * @param <H> type of module handler. It can be {@link TriggerHandler}, {@link ConditionHandler} or
  *            {@link ActionHandler}
  */
+@NonNullByDefault
 public abstract class AbstractCompositeModuleHandler<M extends Module, MT extends ModuleType, H extends ModuleHandler>
         implements ModuleHandler {
 
-    protected LinkedHashMap<M, H> moduleHandlerMap;
+    protected LinkedHashMap<M, @Nullable H> moduleHandlerMap;
     protected M module;
     protected MT moduleType;
 
@@ -64,7 +67,7 @@ public abstract class AbstractCompositeModuleHandler<M extends Module, MT extend
      * @param mapModuleToHandler map containing pairs of child modules instances (defined by module type) and their
      *            handlers
      */
-    public AbstractCompositeModuleHandler(M module, MT moduleType, LinkedHashMap<M, H> mapModuleToHandler) {
+    public AbstractCompositeModuleHandler(M module, MT moduleType, LinkedHashMap<M, @Nullable H> mapModuleToHandler) {
         this.module = module;
         this.moduleType = moduleType;
         this.moduleHandlerMap = mapModuleToHandler;
@@ -102,17 +105,20 @@ public abstract class AbstractCompositeModuleHandler<M extends Module, MT extend
                 childHandler.dispose();
             }
         }
-        moduleHandlerMap = null;
+        moduleHandlerMap.clear();
     }
 
     @Override
     public void setCallback(ModuleHandlerCallback callback) {
         List<M> children = getChildren();
         for (M child : children) {
+            @Nullable
             H handler = moduleHandlerMap.get(child);
+            if (handler != null) {
                 handler.setCallback(callback);
             }
         }
+    }
 
     protected abstract List<M> getChildren();
 }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/composite/CompositeActionHandler.java

@@ -20,6 +20,8 @@ import java.util.Map;
 import java.util.Map.Entry;
 import java.util.StringTokenizer;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Action;
 import org.openhab.core.automation.handler.ActionHandler;
 import org.openhab.core.automation.type.CompositeActionType;
@@ -34,6 +36,7 @@ import org.openhab.core.automation.util.ReferenceResolver;
  *
  * @author Yordan Mihaylov - Initial contribution
  */
+@NonNullByDefault
 public class CompositeActionHandler extends AbstractCompositeModuleHandler<Action, CompositeActionType, ActionHandler>
         implements ActionHandler {
 
@@ -50,7 +53,7 @@ public class CompositeActionHandler extends AbstractCompositeModuleHandler<Actio
      * @param ruleUID UID of rule where the parent action is part of.
      */
     public CompositeActionHandler(Action action, CompositeActionType mt,
-            LinkedHashMap<Action, ActionHandler> mapModuleToHandler, String ruleUID) {
+            LinkedHashMap<Action, @Nullable ActionHandler> mapModuleToHandler, String ruleUID) {
         super(action, mt, mapModuleToHandler);
         compositeOutputs = getCompositeOutputMap(moduleType.getOutputs());
     }
@@ -61,14 +64,14 @@ public class CompositeActionHandler extends AbstractCompositeModuleHandler<Actio
      * @see org.openhab.core.automation.handler.ActionHandler#execute(java.util.Map)
      */
     @Override
-    public Map<String, Object> execute(Map<String, Object> context) {
+    public @Nullable Map<String, Object> execute(Map<String, Object> context) {
         final Map<String, Object> result = new HashMap<>();
         final List<Action> children = getChildren();
         final Map<String, Object> compositeContext = getCompositeContext(context);
         for (Action child : children) {
             ActionHandler childHandler = moduleHandlerMap.get(child);
             Map<String, Object> childContext = Collections.unmodifiableMap(getChildContext(child, compositeContext));
-            Map<String, Object> childResults = childHandler.execute(childContext);
+            Map<String, Object> childResults = childHandler == null ? null : childHandler.execute(childContext);
             if (childResults != null) {
                 for (Entry<String, Object> childResult : childResults.entrySet()) {
                     String childOuputName = child.getId() + "." + childResult.getKey();
@@ -91,7 +94,7 @@ public class CompositeActionHandler extends AbstractCompositeModuleHandler<Actio
     }
 
     /**
-     * Create a map of links between child outputs and parent outputs. These links are base on the refecences defined in
+     * Create a map of links between child outputs and parent outputs. These links are base on the references defined in
      * the outputs of parent action.
      *
      * @param outputs outputs of the parent action. The action of {@link CompositeActionType}
@@ -99,7 +102,6 @@ public class CompositeActionHandler extends AbstractCompositeModuleHandler<Actio
      */
     protected Map<String, Output> getCompositeOutputMap(List<Output> outputs) {
         Map<String, Output> result = new HashMap<>(11);
-        if (outputs != null) {
         for (Output output : outputs) {
             String refs = output.getReference();
             if (refs != null) {
@@ -118,7 +120,6 @@ public class CompositeActionHandler extends AbstractCompositeModuleHandler<Actio
                 }
             }
         }
-        }
         return result;
     }
 

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/composite/CompositeConditionHandler.java

@@ -17,6 +17,8 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Condition;
 import org.openhab.core.automation.handler.ConditionHandler;
 import org.openhab.core.automation.type.CompositeConditionType;
@@ -28,12 +30,13 @@ import org.openhab.core.automation.type.CompositeConditionType;
  *
  * @author Yordan Mihaylov - Initial contribution
  */
+@NonNullByDefault
 public class CompositeConditionHandler
         extends AbstractCompositeModuleHandler<Condition, CompositeConditionType, ConditionHandler>
         implements ConditionHandler {
 
     public CompositeConditionHandler(Condition condition, CompositeConditionType mt,
-            LinkedHashMap<Condition, ConditionHandler> mapModuleToHandler, String ruleUID) {
+            LinkedHashMap<Condition, @Nullable ConditionHandler> mapModuleToHandler, String ruleUID) {
         super(condition, mt, mapModuleToHandler);
     }
 

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/composite/CompositeModuleHandlerFactory.java

@@ -19,6 +19,8 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Action;
 import org.openhab.core.automation.Condition;
 import org.openhab.core.automation.Module;
@@ -53,6 +55,7 @@ import org.slf4j.LoggerFactory;
  *
  * @author Yordan Mihaylov - Initial contribution
  */
+@NonNullByDefault
 public class CompositeModuleHandlerFactory extends BaseModuleHandlerFactory implements ModuleHandlerFactory {
 
     private final ModuleTypeRegistry mtRegistry;
@@ -116,13 +119,13 @@ public class CompositeModuleHandlerFactory extends BaseModuleHandlerFactory impl
     }
 
     @Override
-    public ModuleHandler internalCreate(Module module, String ruleUID) {
+    public @Nullable ModuleHandler internalCreate(Module module, String ruleUID) {
         ModuleHandler handler = null;
         String moduleType = module.getTypeUID();
         ModuleType mt = mtRegistry.get(moduleType);
         if (mt instanceof CompositeTriggerType) {
             List<Trigger> childModules = ((CompositeTriggerType) mt).getChildren();
-            LinkedHashMap<Trigger, TriggerHandler> mapModuleToHandler = getChildHandlers(module.getId(),
+            LinkedHashMap<Trigger, @Nullable TriggerHandler> mapModuleToHandler = getChildHandlers(module.getId(),
                     module.getConfiguration(), childModules, ruleUID);
             if (mapModuleToHandler != null) {
                 handler = new CompositeTriggerHandler((Trigger) module, (CompositeTriggerType) mt, mapModuleToHandler,
@@ -130,7 +133,7 @@ public class CompositeModuleHandlerFactory extends BaseModuleHandlerFactory impl
             }
         } else if (mt instanceof CompositeConditionType) {
             List<Condition> childModules = ((CompositeConditionType) mt).getChildren();
-            LinkedHashMap<Condition, ConditionHandler> mapModuleToHandler = getChildHandlers(module.getId(),
+            LinkedHashMap<Condition, @Nullable ConditionHandler> mapModuleToHandler = getChildHandlers(module.getId(),
                     module.getConfiguration(), childModules, ruleUID);
             if (mapModuleToHandler != null) {
                 handler = new CompositeConditionHandler((Condition) module, (CompositeConditionType) mt,
@@ -138,7 +141,7 @@ public class CompositeModuleHandlerFactory extends BaseModuleHandlerFactory impl
             }
         } else if (mt instanceof CompositeActionType) {
             List<Action> childModules = ((CompositeActionType) mt).getChildren();
-            LinkedHashMap<Action, ActionHandler> mapModuleToHandler = getChildHandlers(module.getId(),
+            LinkedHashMap<Action, @Nullable ActionHandler> mapModuleToHandler = getChildHandlers(module.getId(),
                     module.getConfiguration(), childModules, ruleUID);
             if (mapModuleToHandler != null) {
                 handler = new CompositeActionHandler((Action) module, (CompositeActionType) mt, mapModuleToHandler,
@@ -170,8 +173,8 @@ public class CompositeModuleHandlerFactory extends BaseModuleHandlerFactory impl
      *         handler.
      */
     @SuppressWarnings("unchecked")
-    private <T extends Module, MT extends ModuleHandler> LinkedHashMap<T, MT> getChildHandlers(String compositeModuleId,
+    private <T extends Module, @Nullable MT extends ModuleHandler> @Nullable LinkedHashMap<T, MT> getChildHandlers(
-            Configuration compositeConfig, List<T> childModules, String childModulePrefix) {
+            String compositeModuleId, Configuration compositeConfig, List<T> childModules, String childModulePrefix) {
         LinkedHashMap<T, MT> mapModuleToHandler = new LinkedHashMap<>();
         for (T child : childModules) {
             String ruleId = getRuleId(childModulePrefix);

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/composite/CompositeTriggerHandler.java

@@ -19,6 +19,7 @@ import java.util.Map;
 import java.util.StringTokenizer;
 import java.util.concurrent.ScheduledExecutorService;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.ModuleHandlerCallback;
 import org.openhab.core.automation.RuleStatus;
@@ -38,11 +39,12 @@ import org.openhab.core.automation.util.ReferenceResolver;
  *
  * @author Yordan Mihaylov - Initial contribution
  */
+@NonNullByDefault
 public class CompositeTriggerHandler
         extends AbstractCompositeModuleHandler<Trigger, CompositeTriggerType, TriggerHandler>
         implements TriggerHandler, TriggerHandlerCallback {
 
-    private TriggerHandlerCallback callback;
+    private @NonNullByDefault({}) TriggerHandlerCallback callback;
 
     /**
      * Constructor of this system handler.
@@ -53,7 +55,7 @@ public class CompositeTriggerHandler
      * @param ruleUID UID of rule where the parent trigger is part of
      */
     public CompositeTriggerHandler(Trigger trigger, CompositeTriggerType mt,
-            LinkedHashMap<Trigger, TriggerHandler> mapModuleToHandler, String ruleUID) {
+            LinkedHashMap<Trigger, @Nullable TriggerHandler> mapModuleToHandler, String ruleUID) {
         super(trigger, mt, mapModuleToHandler);
     }
 
@@ -125,10 +127,12 @@ public class CompositeTriggerHandler
             List<Trigger> children = getChildren();
             for (Trigger child : children) {
                 TriggerHandler handler = moduleHandlerMap.get(child);
+                if (handler != null) {
                     handler.setCallback(this);
                 }
             }
         }
+    }
 
     @Override
     public void dispose() {
@@ -142,7 +146,7 @@ public class CompositeTriggerHandler
     }
 
     @Override
-    public Boolean isEnabled(String ruleUID) {
+    public @Nullable Boolean isEnabled(String ruleUID) {
         return callback.isEnabled(ruleUID);
     }
 
@@ -152,12 +156,12 @@ public class CompositeTriggerHandler
     }
 
     @Override
-    public RuleStatusInfo getStatusInfo(String ruleUID) {
+    public @Nullable RuleStatusInfo getStatusInfo(String ruleUID) {
         return callback.getStatusInfo(ruleUID);
     }
 
     @Override
-    public RuleStatus getStatus(String ruleUID) {
+    public @Nullable RuleStatus getStatus(String ruleUID) {
         return callback.getStatus(ruleUID);
     }
 
@@ -167,7 +171,7 @@ public class CompositeTriggerHandler
     }
 
     @Override
-    public void runNow(String uid, boolean considerConditions, Map<String, Object> context) {
+    public void runNow(String uid, boolean considerConditions, @Nullable Map<String, Object> context) {
         callback.runNow(uid, considerConditions, context);
     }
 }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/factory/CoreModuleHandlerFactory.java

@@ -15,6 +15,8 @@ package org.openhab.core.automation.internal.module.factory;
 import java.util.Collection;
 import java.util.List;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Action;
 import org.openhab.core.automation.Condition;
 import org.openhab.core.automation.Module;
@@ -55,6 +57,7 @@ import org.slf4j.LoggerFactory;
  * @author Kai Kreuzer - refactored and simplified customized module handling
  */
 @Component
+@NonNullByDefault
 public class CoreModuleHandlerFactory extends BaseModuleHandlerFactory implements ModuleHandlerFactory {
 
     private final Logger logger = LoggerFactory.getLogger(CoreModuleHandlerFactory.class);
@@ -76,8 +79,11 @@ public class CoreModuleHandlerFactory extends BaseModuleHandlerFactory implement
     private BundleContext bundleContext;
 
     @Activate
-    protected void activate(BundleContext bundleContext) {
+    public CoreModuleHandlerFactory(BundleContext bundleContext, final @Reference EventPublisher eventPublisher,
+            final @Reference ItemRegistry itemRegistry) {
         this.bundleContext = bundleContext;
+        this.eventPublisher = eventPublisher;
+        this.itemRegistry = itemRegistry;
     }
 
     @Override
@@ -91,78 +97,8 @@ public class CoreModuleHandlerFactory extends BaseModuleHandlerFactory implement
         return TYPES;
     }
 
-    /**
-     * the itemRegistry was added (called by serviceTracker)
-     *
-     * @param itemRegistry
-     */
-    @Reference
-    protected void setItemRegistry(ItemRegistry itemRegistry) {
-        this.itemRegistry = itemRegistry;
-        for (ModuleHandler handler : getHandlers().values()) {
-            if (handler instanceof ItemStateConditionHandler) {
-                ((ItemStateConditionHandler) handler).setItemRegistry(this.itemRegistry);
-            } else if (handler instanceof ItemCommandActionHandler) {
-                ((ItemCommandActionHandler) handler).setItemRegistry(this.itemRegistry);
-            } else if (handler instanceof GroupCommandTriggerHandler) {
-                ((GroupCommandTriggerHandler) handler).setItemRegistry(this.itemRegistry);
-            } else if (handler instanceof GroupStateTriggerHandler) {
-                ((GroupStateTriggerHandler) handler).setItemRegistry(this.itemRegistry);
-            }
-        }
-    }
-
-    /**
-     * unsetter for itemRegistry (called by serviceTracker)
-     *
-     * @param itemRegistry
-     */
-    protected void unsetItemRegistry(ItemRegistry itemRegistry) {
-        for (ModuleHandler handler : getHandlers().values()) {
-            if (handler instanceof ItemStateConditionHandler) {
-                ((ItemStateConditionHandler) handler).unsetItemRegistry(this.itemRegistry);
-            } else if (handler instanceof ItemCommandActionHandler) {
-                ((ItemCommandActionHandler) handler).unsetItemRegistry(this.itemRegistry);
-            } else if (handler instanceof GroupCommandTriggerHandler) {
-                ((GroupCommandTriggerHandler) handler).unsetItemRegistry(this.itemRegistry);
-            } else if (handler instanceof GroupStateTriggerHandler) {
-                ((GroupStateTriggerHandler) handler).unsetItemRegistry(this.itemRegistry);
-            }
-        }
-        this.itemRegistry = null;
-    }
-
-    /**
-     * setter for the eventPublisher (called by serviceTracker)
-     *
-     * @param eventPublisher
-     */
-    @Reference
-    protected void setEventPublisher(EventPublisher eventPublisher) {
-        this.eventPublisher = eventPublisher;
-        for (ModuleHandler handler : getHandlers().values()) {
-            if (handler instanceof ItemCommandActionHandler) {
-                ((ItemCommandActionHandler) handler).setEventPublisher(eventPublisher);
-            }
-        }
-    }
-
-    /**
-     * unsetter for eventPublisher (called by serviceTracker)
-     *
-     * @param eventPublisher
-     */
-    protected void unsetEventPublisher(EventPublisher eventPublisher) {
-        this.eventPublisher = null;
-        for (ModuleHandler handler : getHandlers().values()) {
-            if (handler instanceof ItemCommandActionHandler) {
-                ((ItemCommandActionHandler) handler).unsetEventPublisher(eventPublisher);
-            }
-        }
-    }
-
     @Override
-    protected synchronized ModuleHandler internalCreate(final Module module, final String ruleUID) {
+    protected synchronized @Nullable ModuleHandler internalCreate(final Module module, final String ruleUID) {
         logger.trace("create {} -> {} : {}", module.getId(), module.getTypeUID(), ruleUID);
         final String moduleTypeUID = module.getTypeUID();
         if (module instanceof Trigger) {
@@ -182,22 +118,15 @@ public class CoreModuleHandlerFactory extends BaseModuleHandlerFactory implement
                     || ItemStateTriggerHandler.UPDATE_MODULE_TYPE_ID.equals(moduleTypeUID)) {
                 return new ItemStateTriggerHandler((Trigger) module, bundleContext);
             } else if (GroupCommandTriggerHandler.MODULE_TYPE_ID.equals(moduleTypeUID)) {
-                final GroupCommandTriggerHandler handler = new GroupCommandTriggerHandler((Trigger) module,
+                return new GroupCommandTriggerHandler((Trigger) module, bundleContext, itemRegistry);
-                        bundleContext);
-                handler.setItemRegistry(itemRegistry);
-                return handler;
             } else if (GroupStateTriggerHandler.CHANGE_MODULE_TYPE_ID.equals(moduleTypeUID)
                     || GroupStateTriggerHandler.UPDATE_MODULE_TYPE_ID.equals(moduleTypeUID)) {
-                final GroupStateTriggerHandler handler = new GroupStateTriggerHandler((Trigger) module, bundleContext);
+                return new GroupStateTriggerHandler((Trigger) module, bundleContext, itemRegistry);
-                handler.setItemRegistry(itemRegistry);
-                return handler;
             }
         } else if (module instanceof Condition) {
             // Handle conditions
             if (ItemStateConditionHandler.ITEM_STATE_CONDITION.equals(moduleTypeUID)) {
-                ItemStateConditionHandler handler = new ItemStateConditionHandler((Condition) module);
+                return new ItemStateConditionHandler((Condition) module, itemRegistry);
-                handler.setItemRegistry(itemRegistry);
-                return handler;
             } else if (GenericEventConditionHandler.MODULETYPE_ID.equals(moduleTypeUID)) {
                 return new GenericEventConditionHandler((Condition) module);
             } else if (CompareConditionHandler.MODULE_TYPE.equals(moduleTypeUID)) {
@@ -206,10 +135,7 @@ public class CoreModuleHandlerFactory extends BaseModuleHandlerFactory implement
         } else if (module instanceof Action) {
             // Handle actions
             if (ItemCommandActionHandler.ITEM_COMMAND_ACTION.equals(moduleTypeUID)) {
-                final ItemCommandActionHandler postCommandActionHandler = new ItemCommandActionHandler((Action) module);
+                return new ItemCommandActionHandler((Action) module, eventPublisher, itemRegistry);
-                postCommandActionHandler.setEventPublisher(eventPublisher);
-                postCommandActionHandler.setItemRegistry(itemRegistry);
-                return postCommandActionHandler;
             } else if (ItemStateUpdateActionHandler.ITEM_STATE_UPDATE_ACTION.equals(moduleTypeUID)) {
                 return new ItemStateUpdateActionHandler((Action) module, eventPublisher, itemRegistry);
             } else if (RuleEnablementActionHandler.UID.equals(moduleTypeUID)) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/AnnotationActionHandler.java

@@ -21,6 +21,8 @@ import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Action;
 import org.openhab.core.automation.annotation.ActionInput;
 import org.openhab.core.automation.handler.BaseActionModuleHandler;
@@ -35,6 +37,7 @@ import org.slf4j.LoggerFactory;
  *
  * @author Stefan Triller - Initial contribution
  */
+@NonNullByDefault
 public class AnnotationActionHandler extends BaseActionModuleHandler {
 
     private static final String MODULE_RESULT = "result";
@@ -54,11 +57,11 @@ public class AnnotationActionHandler extends BaseActionModuleHandler {
     }
 
     @Override
-    public Map<String, Object> execute(Map<String, Object> context) {
+    public @Nullable Map<String, Object> execute(Map<String, Object> context) {
         Map<String, Object> output = new HashMap<>();
 
         Annotation[][] annotations = method.getParameterAnnotations();
-        List<Object> args = new ArrayList<>();
+        List<@Nullable Object> args = new ArrayList<>();
 
         for (int i = 0; i < annotations.length; i++) {
             Annotation[] annotationsOnParam = annotations[i];
@@ -90,6 +93,7 @@ public class AnnotationActionHandler extends BaseActionModuleHandler {
         if (result != null) {
             if (result instanceof Map<?, ?>) {
                 try {
+                    @SuppressWarnings("unchecked")
                     Map<String, Object> resultMap = (Map<String, Object>) result;
                     for (Entry<String, Object> entry : resultMap.entrySet()) {
                         if (hasOutput(moduleType, entry.getKey())) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/ChannelEventTriggerHandler.java

@@ -86,6 +86,7 @@ public class ChannelEventTriggerHandler extends BaseTriggerModuleHandler impleme
         if (event instanceof ChannelTriggeredEvent) {
             ChannelTriggeredEvent cte = (ChannelTriggeredEvent) event;
             if (channelUID.equals(cte.getChannel())) {
+                String eventOnChannel = this.eventOnChannel;
                 logger.trace("->FILTER: {}:{}", cte.getEvent(), eventOnChannel);
                 eventMatches = eventOnChannel == null || eventOnChannel.isBlank()
                         || eventOnChannel.equals(cte.getEvent());

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/CompareConditionHandler.java

@@ -17,6 +17,7 @@ import java.lang.reflect.Method;
 import java.util.List;
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Condition;
 import org.openhab.core.automation.handler.BaseConditionModuleHandler;
@@ -31,6 +32,7 @@ import org.slf4j.LoggerFactory;
  *
  * @author Benedikt Niehues - Initial contribution
  */
+@NonNullByDefault
 public class CompareConditionHandler extends BaseConditionModuleHandler {
 
     public static final String MODULE_TYPE = "core.GenericCompareCondition";
@@ -47,7 +49,7 @@ public class CompareConditionHandler extends BaseConditionModuleHandler {
     }
 
     @Override
-    public boolean isSatisfied(Map<String, Object> context) {
+    public boolean isSatisfied(Map<String, @Nullable Object> context) {
         Object operatorObj = this.module.getConfiguration().get(OPERATOR);
         String operator = (operatorObj != null && operatorObj instanceof String) ? (String) operatorObj : null;
         Object rightObj = this.module.getConfiguration().get(RIGHT_OP);
@@ -151,7 +153,7 @@ public class CompareConditionHandler extends BaseConditionModuleHandler {
         throw new UncomparableException();
     }
 
-    private @Nullable Object getRightOperandValue(String rightOperandString2, Object toCompare) {
+    private @Nullable Object getRightOperandValue(String rightOperandString2, @Nullable Object toCompare) {
         if ("null".equals(rightOperandString2)) {
             return rightOperandString2;
         }
@@ -169,7 +171,7 @@ public class CompareConditionHandler extends BaseConditionModuleHandler {
         return null;
     }
 
-    private Object getCompareValue(Object leftObj, String leftObjFieldName) {
+    private @Nullable Object getCompareValue(@Nullable Object leftObj, @Nullable String leftObjFieldName) {
         if (leftObj == null || leftObjFieldName == null || leftObjFieldName.isEmpty() || leftObj instanceof String
                 || leftObj instanceof Integer || leftObj instanceof Long || leftObj instanceof Double) {
             return leftObj;

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/DayOfWeekConditionHandler.java

@@ -18,6 +18,7 @@ import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.Condition;
 import org.openhab.core.automation.handler.BaseConditionModuleHandler;
 import org.openhab.core.automation.handler.TimeBasedConditionHandler;
@@ -29,6 +30,7 @@ import org.slf4j.LoggerFactory;
  *
  * @author Kai Kreuzer - Initial contribution
  */
+@NonNullByDefault
 public class DayOfWeekConditionHandler extends BaseConditionModuleHandler implements TimeBasedConditionHandler {
 
     public static final String MODULE_TYPE_ID = "timer.DayOfWeekCondition";

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/EphemerisConditionHandler.java

@@ -64,20 +64,20 @@ public class EphemerisConditionHandler extends BaseModuleHandler<Condition> impl
 
     @Override
     public boolean isSatisfiedAt(ZonedDateTime time) {
-        time = time.plusDays(offset); // Apply offset to time
+        ZonedDateTime offsetTime = time.plusDays(offset); // Apply offset to time
         switch (module.getTypeUID()) {
             case HOLIDAY_MODULE_TYPE_ID:
-                return ephemerisManager.isBankHoliday(time);
+                return ephemerisManager.isBankHoliday(offsetTime);
             case NOT_HOLIDAY_MODULE_TYPE_ID:
-                return !ephemerisManager.isBankHoliday(time);
+                return !ephemerisManager.isBankHoliday(offsetTime);
             case WEEKEND_MODULE_TYPE_ID:
-                return ephemerisManager.isWeekend(time);
+                return ephemerisManager.isWeekend(offsetTime);
             case WEEKDAY_MODULE_TYPE_ID:
-                return !ephemerisManager.isWeekend(time);
+                return !ephemerisManager.isWeekend(offsetTime);
             case DAYSET_MODULE_TYPE_ID:
                 final String dayset = this.dayset;
                 if (dayset != null) {
-                    return ephemerisManager.isInDayset(dayset, time);
+                    return ephemerisManager.isInDayset(dayset, offsetTime);
                 }
                 break;
         }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/GenericCronTriggerHandler.java

@@ -12,6 +12,8 @@
  */
 package org.openhab.core.automation.internal.module.handler;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.ModuleHandlerCallback;
 import org.openhab.core.automation.Trigger;
 import org.openhab.core.automation.handler.BaseTriggerModuleHandler;
@@ -32,6 +34,7 @@ import org.slf4j.LoggerFactory;
  * @author Christoph Knauf - Initial contribution
  * @author Yordan Mihaylov - Remove Quarz lib dependency
  */
+@NonNullByDefault
 public class GenericCronTriggerHandler extends BaseTriggerModuleHandler
         implements SchedulerRunnable, TimeBasedTriggerHandler {
 
@@ -45,7 +48,7 @@ public class GenericCronTriggerHandler extends BaseTriggerModuleHandler
 
     private final CronScheduler scheduler;
     private final String expression;
-    private ScheduledCompletableFuture<?> schedule;
+    private @Nullable ScheduledCompletableFuture<?> schedule;
 
     public GenericCronTriggerHandler(Trigger module, CronScheduler scheduler) {
         super(module);
@@ -77,7 +80,7 @@ public class GenericCronTriggerHandler extends BaseTriggerModuleHandler
     @Override
     public void run() {
         if (callback != null) {
-            ((TriggerHandlerCallback) callback).triggered(module, null);
+            ((TriggerHandlerCallback) callback).triggered(module);
         } else {
             logger.debug("Tried to trigger, but callback isn't available!");
         }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/GenericEventConditionHandler.java

@@ -14,6 +14,8 @@ package org.openhab.core.automation.internal.module.handler;
 
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Condition;
 import org.openhab.core.automation.handler.BaseConditionModuleHandler;
 import org.openhab.core.events.Event;
@@ -26,6 +28,7 @@ import org.slf4j.LoggerFactory;
  * @author Benedikt Niehues - Initial contribution
  * @author Kai Kreuzer - refactored and simplified customized module handling
  */
+@NonNullByDefault
 public class GenericEventConditionHandler extends BaseConditionModuleHandler {
 
     public static final String MODULETYPE_ID = "core.GenericEventCondition";
@@ -41,7 +44,7 @@ public class GenericEventConditionHandler extends BaseConditionModuleHandler {
         super(module);
     }
 
-    private boolean isConfiguredAndMatches(String keyParam, String value) {
+    private boolean isConfiguredAndMatches(String keyParam, @Nullable String value) {
         Object mo = module.getConfiguration().get(keyParam);
         String configValue = mo != null && mo instanceof String ? (String) mo : null;
         if (configValue != null) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/GenericEventTriggerHandler.java

@@ -18,6 +18,9 @@ import java.util.Hashtable;
 import java.util.Map;
 import java.util.Set;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.core.automation.ModuleHandlerCallback;
 import org.openhab.core.automation.Trigger;
 import org.openhab.core.automation.handler.BaseTriggerModuleHandler;
 import org.openhab.core.automation.handler.TriggerHandlerCallback;
@@ -41,6 +44,7 @@ import org.slf4j.LoggerFactory;
  * @author Benedikt Niehues - Initial contribution
  * @author Kai Kreuzer - refactored and simplified customized module handling
  */
+@NonNullByDefault
 public class GenericEventTriggerHandler extends BaseTriggerModuleHandler implements EventSubscriber, EventFilter {
 
     public static final String MODULE_TYPE_ID = "core.GenericEventTrigger";
@@ -56,7 +60,7 @@ public class GenericEventTriggerHandler extends BaseTriggerModuleHandler impleme
     private final Set<String> types;
     private final BundleContext bundleContext;
 
-    private ServiceRegistration<?> eventSubscriberRegistration;
+    private @Nullable ServiceRegistration<?> eventSubscriberRegistration;
 
     public GenericEventTriggerHandler(Trigger module, BundleContext bundleContext) {
         super(module);
@@ -81,12 +85,13 @@ public class GenericEventTriggerHandler extends BaseTriggerModuleHandler impleme
     }
 
     @Override
-    public EventFilter getEventFilter() {
+    public @Nullable EventFilter getEventFilter() {
         return this;
     }
 
     @Override
     public void receive(Event event) {
+        ModuleHandlerCallback callback = this.callback;
         if (callback != null) {
             logger.trace("Received Event: Source: {} Topic: {} Type: {}  Payload: {}", event.getSource(),
                     event.getTopic(), event.getType(), event.getPayload());

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/GroupCommandTriggerHandler.java

@@ -53,6 +53,7 @@ public class GroupCommandTriggerHandler extends BaseTriggerModuleHandler impleme
 
     private final Set<String> types;
     private final BundleContext bundleContext;
+    private final ItemRegistry itemRegistry;
 
     public static final String MODULE_TYPE_ID = "core.GroupCommandTrigger";
 
@@ -60,14 +61,14 @@ public class GroupCommandTriggerHandler extends BaseTriggerModuleHandler impleme
     public static final String CFG_COMMAND = "command";
 
     private ServiceRegistration<?> eventSubscriberRegistration;
-    private @Nullable ItemRegistry itemRegistry;
 
-    public GroupCommandTriggerHandler(Trigger module, BundleContext bundleContext) {
+    public GroupCommandTriggerHandler(Trigger module, BundleContext bundleContext, ItemRegistry itemRegistry) {
         super(module);
         this.groupName = (String) module.getConfiguration().get(CFG_GROUPNAME);
         this.command = (String) module.getConfiguration().get(CFG_COMMAND);
         this.types = Set.of(ItemCommandEvent.TYPE);
         this.bundleContext = bundleContext;
+        this.itemRegistry = itemRegistry;
         Dictionary<String, Object> properties = new Hashtable<>();
         this.topic = "openhab/items/";
         properties.put("event.topics", topic);
@@ -95,9 +96,9 @@ public class GroupCommandTriggerHandler extends BaseTriggerModuleHandler impleme
             if (event instanceof ItemCommandEvent) {
                 ItemCommandEvent icEvent = (ItemCommandEvent) event;
                 String itemName = icEvent.getItemName();
-                if (itemRegistry != null) {
                 Item item = itemRegistry.get(itemName);
                 if (item != null && item.getGroupNames().contains(groupName)) {
+                    String command = this.command;
                     Command itemCommand = icEvent.getItemCommand();
                     if (command == null || command.equals(itemCommand.toFullString())) {
                         values.put("triggeringItem", item);
@@ -109,7 +110,6 @@ public class GroupCommandTriggerHandler extends BaseTriggerModuleHandler impleme
             }
         }
     }
-    }
 
     /**
      * do the cleanup: unregistering eventSubscriber...
@@ -125,12 +125,4 @@ public class GroupCommandTriggerHandler extends BaseTriggerModuleHandler impleme
         logger.trace("->FILTER: {}", event.getTopic());
         return event.getTopic().startsWith(topic);
     }
-
-    public void setItemRegistry(ItemRegistry itemRegistry) {
-        this.itemRegistry = itemRegistry;
-    }
-
-    public void unsetItemRegistry(ItemRegistry itemRegistry) {
-        this.itemRegistry = null;
-    }
 }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/GroupStateTriggerHandler.java

@@ -61,11 +61,11 @@ public class GroupStateTriggerHandler extends BaseTriggerModuleHandler implement
     private final String previousState;
     private Set<String> types;
     private final BundleContext bundleContext;
-    private @Nullable ItemRegistry itemRegistry;
+    private ItemRegistry itemRegistry;
 
     private ServiceRegistration<?> eventSubscriberRegistration;
 
-    public GroupStateTriggerHandler(Trigger module, BundleContext bundleContext) {
+    public GroupStateTriggerHandler(Trigger module, BundleContext bundleContext, ItemRegistry itemRegistry) {
         super(module);
         this.groupName = (String) module.getConfiguration().get(CFG_GROUPNAME);
         this.state = (String) module.getConfiguration().get(CFG_STATE);
@@ -76,6 +76,7 @@ public class GroupStateTriggerHandler extends BaseTriggerModuleHandler implement
             this.types = Set.of(ItemStateChangedEvent.TYPE, GroupItemStateChangedEvent.TYPE);
         }
         this.bundleContext = bundleContext;
+        this.itemRegistry = itemRegistry;
         Dictionary<String, Object> properties = new Hashtable<>();
         properties.put("event.topics", "openhab/items/*");
         eventSubscriberRegistration = this.bundleContext.registerService(EventSubscriber.class.getName(), this,
@@ -101,7 +102,6 @@ public class GroupStateTriggerHandler extends BaseTriggerModuleHandler implement
             if (event instanceof ItemStateEvent && UPDATE_MODULE_TYPE_ID.equals(module.getTypeUID())) {
                 ItemStateEvent isEvent = (ItemStateEvent) event;
                 String itemName = isEvent.getItemName();
-                if (itemRegistry != null) {
                 Item item = itemRegistry.get(itemName);
                 if (item != null && item.getGroupNames().contains(groupName)) {
                     State state = isEvent.getItemState();
@@ -113,11 +113,9 @@ public class GroupStateTriggerHandler extends BaseTriggerModuleHandler implement
                         cb.triggered(this.module, values);
                     }
                 }
-                }
             } else if (event instanceof ItemStateChangedEvent && CHANGE_MODULE_TYPE_ID.equals(module.getTypeUID())) {
                 ItemStateChangedEvent iscEvent = (ItemStateChangedEvent) event;
                 String itemName = iscEvent.getItemName();
-                if (itemRegistry != null) {
                 Item item = itemRegistry.get(itemName);
                 if (item != null && item.getGroupNames().contains(groupName)) {
                     State state = iscEvent.getItemState();
@@ -135,7 +133,6 @@ public class GroupStateTriggerHandler extends BaseTriggerModuleHandler implement
             }
         }
     }
-    }
 
     private boolean stateMatches(@Nullable String requiredState, State state) {
         if (requiredState == null) {
@@ -160,12 +157,4 @@ public class GroupStateTriggerHandler extends BaseTriggerModuleHandler implement
         logger.trace("->FILTER: {}:{}", event.getTopic(), groupName);
         return event.getTopic().startsWith("openhab/items/");
     }
-
-    public void setItemRegistry(ItemRegistry itemRegistry) {
-        this.itemRegistry = itemRegistry;
-    }
-
-    public void unsetItemRegistry(ItemRegistry itemRegistry) {
-        this.itemRegistry = null;
-    }
 }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/ItemCommandActionHandler.java

@@ -14,6 +14,8 @@ package org.openhab.core.automation.internal.module.handler;
 
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Action;
 import org.openhab.core.automation.handler.BaseActionModuleHandler;
 import org.openhab.core.events.EventPublisher;
@@ -34,6 +36,7 @@ import org.slf4j.LoggerFactory;
  * @author Kai Kreuzer - refactored and simplified customized module handling
  * @author Stefan Triller - use command from input first and if not set, use command from configuration
  */
+@NonNullByDefault
 public class ItemCommandActionHandler extends BaseActionModuleHandler {
 
     public static final String ITEM_COMMAND_ACTION = "core.ItemCommandAction";
@@ -42,8 +45,8 @@ public class ItemCommandActionHandler extends BaseActionModuleHandler {
 
     private final Logger logger = LoggerFactory.getLogger(ItemCommandActionHandler.class);
 
-    private ItemRegistry itemRegistry;
+    private final EventPublisher eventPublisher;
-    private EventPublisher eventPublisher;
+    private final ItemRegistry itemRegistry;
 
     /**
      * constructs a new ItemCommandActionHandler
@@ -51,58 +54,18 @@ public class ItemCommandActionHandler extends BaseActionModuleHandler {
      * @param module
      * @param moduleTypes
      */
-    public ItemCommandActionHandler(Action module) {
+    public ItemCommandActionHandler(Action module, EventPublisher eventPublisher, ItemRegistry itemRegistry) {
         super(module);
-    }
+        this.eventPublisher = eventPublisher;
-
-    /**
-     * setter for itemRegistry, used by DS
-     *
-     * @param itemRegistry
-     */
-    public void setItemRegistry(ItemRegistry itemRegistry) {
         this.itemRegistry = itemRegistry;
     }
 
-    /**
-     * unsetter for itemRegistry, used by DS
-     *
-     * @param itemRegistry
-     */
-    public void unsetItemRegistry(ItemRegistry itemRegistry) {
-        this.itemRegistry = null;
-    }
-
-    /**
-     * setter for eventPublisher used by DS
-     *
-     * @param eventPublisher
-     */
-    public void setEventPublisher(EventPublisher eventPublisher) {
-        this.eventPublisher = eventPublisher;
-    }
-
-    /**
-     * unsetter for eventPublisher used by DS
-     *
-     * @param eventPublisher
-     */
-    public void unsetEventPublisher(EventPublisher eventPublisher) {
-        this.eventPublisher = null;
-    }
-
     @Override
-    public void dispose() {
+    public @Nullable Map<String, Object> execute(Map<String, Object> inputs) {
-        this.eventPublisher = null;
-        this.itemRegistry = null;
-    }
-
-    @Override
-    public Map<String, Object> execute(Map<String, Object> inputs) {
         String itemName = (String) module.getConfiguration().get(ITEM_NAME);
         String command = (String) module.getConfiguration().get(COMMAND);
 
-        if (itemName != null && eventPublisher != null && itemRegistry != null) {
+        if (itemName != null) {
             try {
                 Item item = itemRegistry.getItem(itemName);
 

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/ItemCommandTriggerHandler.java

@@ -18,6 +18,9 @@ import java.util.Hashtable;
 import java.util.Map;
 import java.util.Set;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.core.automation.ModuleHandlerCallback;
 import org.openhab.core.automation.Trigger;
 import org.openhab.core.automation.handler.BaseTriggerModuleHandler;
 import org.openhab.core.automation.handler.TriggerHandlerCallback;
@@ -38,6 +41,7 @@ import org.slf4j.LoggerFactory;
  *
  * @author Kai Kreuzer - Initial contribution
  */
+@NonNullByDefault
 public class ItemCommandTriggerHandler extends BaseTriggerModuleHandler implements EventSubscriber, EventFilter {
 
     public static final String MODULE_TYPE_ID = "core.ItemCommandTrigger";
@@ -48,13 +52,13 @@ public class ItemCommandTriggerHandler extends BaseTriggerModuleHandler implemen
     private final Logger logger = LoggerFactory.getLogger(ItemCommandTriggerHandler.class);
 
     private final String itemName;
-    private final String command;
+    private final @Nullable String command;
     private final String topic;
 
     private final Set<String> types;
     private final BundleContext bundleContext;
 
-    private ServiceRegistration<?> eventSubscriberRegistration;
+    private @Nullable ServiceRegistration<?> eventSubscriberRegistration;
 
     public ItemCommandTriggerHandler(Trigger module, BundleContext bundleContext) {
         super(module);
@@ -75,20 +79,22 @@ public class ItemCommandTriggerHandler extends BaseTriggerModuleHandler implemen
     }
 
     @Override
-    public EventFilter getEventFilter() {
+    public @Nullable EventFilter getEventFilter() {
         return this;
     }
 
     @Override
     public void receive(Event event) {
+        ModuleHandlerCallback callback = this.callback;
         if (callback != null) {
             logger.trace("Received Event: Source: {} Topic: {} Type: {}  Payload: {}", event.getSource(),
                     event.getTopic(), event.getType(), event.getPayload());
             Map<String, Object> values = new HashMap<>();
             if (event instanceof ItemCommandEvent) {
-                Command command = ((ItemCommandEvent) event).getItemCommand();
+                String command = this.command;
-                if (this.command == null || this.command.equals(command.toFullString())) {
+                Command itemCommand = ((ItemCommandEvent) event).getItemCommand();
-                    values.put("command", command);
+                if (command == null || command.equals(itemCommand.toFullString())) {
+                    values.put("command", itemCommand);
                     values.put("event", event);
                     ((TriggerHandlerCallback) callback).triggered(this.module, values);
                 }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/ItemStateConditionHandler.java

@@ -15,7 +15,6 @@ package org.openhab.core.automation.internal.module.handler;
 import java.util.Map;
 
 import org.eclipse.jdt.annotation.NonNullByDefault;
-import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Condition;
 import org.openhab.core.automation.handler.BaseConditionModuleHandler;
 import org.openhab.core.items.Item;
@@ -49,35 +48,13 @@ public class ItemStateConditionHandler extends BaseConditionModuleHandler {
 
     public static final String ITEM_STATE_CONDITION = "core.ItemStateCondition";
 
-    private @Nullable ItemRegistry itemRegistry;
+    private final ItemRegistry itemRegistry;
 
-    public ItemStateConditionHandler(Condition condition) {
+    public ItemStateConditionHandler(Condition condition, ItemRegistry itemRegistry) {
         super(condition);
-    }
-
-    /**
-     * setter for itemRegistry, used by DS
-     *
-     * @param itemRegistry
-     */
-    public void setItemRegistry(ItemRegistry itemRegistry) {
         this.itemRegistry = itemRegistry;
     }
 
-    /**
-     * unsetter for itemRegistry used by DS
-     *
-     * @param itemRegistry
-     */
-    public void unsetItemRegistry(ItemRegistry itemRegistry) {
-        this.itemRegistry = null;
-    }
-
-    @Override
-    public void dispose() {
-        itemRegistry = null;
-    }
-
     @Override
     public boolean isSatisfied(Map<String, Object> inputs) {
         String itemName = (String) module.getConfiguration().get(ITEM_NAME);
@@ -88,10 +65,6 @@ public class ItemStateConditionHandler extends BaseConditionModuleHandler {
                     state);
             return false;
         }
-        if (itemRegistry == null) {
-            logger.error("The ItemRegistry is not available to evaluate the condition.");
-            return false;
-        }
         try {
             logger.debug("ItemStateCondition '{}' checking if {} {} {}", module.getId(), itemName, operator, state);
             switch (operator) {
@@ -174,7 +147,6 @@ public class ItemStateConditionHandler extends BaseConditionModuleHandler {
         return false;
     }
 
-    @SuppressWarnings("null")
     private boolean equalsToItemState(String itemName, String state) throws ItemNotFoundException {
         Item item = itemRegistry.getItem(itemName);
         State compareState = TypeParser.parseState(item.getAcceptedDataTypes(), state);

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/ItemStateTriggerHandler.java

@@ -18,6 +18,9 @@ import java.util.Hashtable;
 import java.util.Map;
 import java.util.Set;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.core.automation.ModuleHandlerCallback;
 import org.openhab.core.automation.Trigger;
 import org.openhab.core.automation.handler.BaseTriggerModuleHandler;
 import org.openhab.core.automation.handler.TriggerHandlerCallback;
@@ -41,6 +44,7 @@ import org.slf4j.LoggerFactory;
  * @author Kai Kreuzer - Initial contribution
  * @author Simon Merschjohann - Initial contribution
  */
+@NonNullByDefault
 public class ItemStateTriggerHandler extends BaseTriggerModuleHandler implements EventSubscriber, EventFilter {
 
     public static final String UPDATE_MODULE_TYPE_ID = "core.ItemStateUpdateTrigger";
@@ -53,12 +57,12 @@ public class ItemStateTriggerHandler extends BaseTriggerModuleHandler implements
     private final Logger logger = LoggerFactory.getLogger(ItemStateTriggerHandler.class);
 
     private final String itemName;
-    private final String state;
+    private final @Nullable String state;
     private final String previousState;
     private Set<String> types;
     private final BundleContext bundleContext;
 
-    private ServiceRegistration<?> eventSubscriberRegistration;
+    private @Nullable ServiceRegistration<?> eventSubscriberRegistration;
 
     public ItemStateTriggerHandler(Trigger module, BundleContext bundleContext) {
         super(module);
@@ -83,28 +87,30 @@ public class ItemStateTriggerHandler extends BaseTriggerModuleHandler implements
     }
 
     @Override
-    public EventFilter getEventFilter() {
+    public @Nullable EventFilter getEventFilter() {
         return this;
     }
 
     @Override
     public void receive(Event event) {
+        ModuleHandlerCallback callback = this.callback;
         if (callback != null) {
             logger.trace("Received Event: Source: {} Topic: {} Type: {}  Payload: {}", event.getSource(),
                     event.getTopic(), event.getType(), event.getPayload());
             Map<String, Object> values = new HashMap<>();
             if (event instanceof ItemStateEvent && UPDATE_MODULE_TYPE_ID.equals(module.getTypeUID())) {
-                State state = ((ItemStateEvent) event).getItemState();
+                String state = this.state;
-                if ((this.state == null || this.state.equals(state.toFullString()))) {
+                State itemState = ((ItemStateEvent) event).getItemState();
-                    values.put("state", state);
+                if ((state == null || state.equals(itemState.toFullString()))) {
+                    values.put("state", itemState);
                 }
             } else if (event instanceof ItemStateChangedEvent && CHANGE_MODULE_TYPE_ID.equals(module.getTypeUID())) {
-                State state = ((ItemStateChangedEvent) event).getItemState();
+                State itemState = ((ItemStateChangedEvent) event).getItemState();
-                State oldState = ((ItemStateChangedEvent) event).getOldItemState();
+                State oldItemState = ((ItemStateChangedEvent) event).getOldItemState();
 
-                if (stateMatches(this.state, state) && stateMatches(this.previousState, oldState)) {
+                if (stateMatches(this.state, itemState) && stateMatches(this.previousState, oldItemState)) {
-                    values.put("oldState", oldState);
+                    values.put("oldState", oldItemState);
-                    values.put("newState", state);
+                    values.put("newState", itemState);
                 }
             }
             if (!values.isEmpty()) {
@@ -114,7 +120,7 @@ public class ItemStateTriggerHandler extends BaseTriggerModuleHandler implements
         }
     }
 
-    private boolean stateMatches(String requiredState, State state) {
+    private boolean stateMatches(@Nullable String requiredState, State state) {
         if (requiredState == null) {
             return true;
         }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/RuleEnablementActionHandler.java

@@ -15,6 +15,8 @@ package org.openhab.core.automation.internal.module.handler;
 import java.util.List;
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Action;
 import org.openhab.core.automation.RuleRegistry;
 import org.openhab.core.automation.handler.BaseActionModuleHandler;
@@ -41,6 +43,7 @@ import org.slf4j.LoggerFactory;
  * @author Plamen Peev - Initial contribution
  * @author Kai Kreuzer - use rule engine instead of registry
  */
+@NonNullByDefault
 public class RuleEnablementActionHandler extends BaseActionModuleHandler {
 
     /**
@@ -91,7 +94,7 @@ public class RuleEnablementActionHandler extends BaseActionModuleHandler {
     }
 
     @Override
-    public Map<String, Object> execute(Map<String, Object> context) {
+    public @Nullable Map<String, Object> execute(Map<String, Object> context) {
         for (String uid : uids) {
             if (callback != null) {
                 callback.setEnabled(uid, enable);

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/RunRuleActionHandler.java

@@ -15,6 +15,8 @@ package org.openhab.core.automation.internal.module.handler;
 import java.util.List;
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Action;
 import org.openhab.core.automation.handler.BaseActionModuleHandler;
 import org.openhab.core.config.core.Configuration;
@@ -39,6 +41,7 @@ import org.slf4j.LoggerFactory;
  * @author Benedikt Niehues - Initial contribution
  * @author Kai Kreuzer - use rule engine instead of registry
  */
+@NonNullByDefault
 public class RunRuleActionHandler extends BaseActionModuleHandler {
 
     /**
@@ -86,7 +89,7 @@ public class RunRuleActionHandler extends BaseActionModuleHandler {
     }
 
     @Override
-    public Map<String, Object> execute(Map<String, Object> context) {
+    public @Nullable Map<String, Object> execute(Map<String, Object> context) {
         // execute each rule after the other; at the moment synchronously
         for (String uid : ruleUIDs) {
             if (callback != null) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/TimeOfDayConditionHandler.java

@@ -17,6 +17,8 @@ import java.time.ZonedDateTime;
 import java.time.temporal.ChronoUnit;
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Condition;
 import org.openhab.core.automation.handler.BaseConditionModuleHandler;
 import org.openhab.core.automation.handler.TimeBasedConditionHandler;
@@ -29,6 +31,7 @@ import org.slf4j.LoggerFactory;
  *
  * @author Dominik Schlierf - Initial contribution
  */
+@NonNullByDefault
 public class TimeOfDayConditionHandler extends BaseConditionModuleHandler implements TimeBasedConditionHandler {
 
     public static final String MODULE_TYPE_ID = "core.TimeOfDayCondition";
@@ -45,11 +48,11 @@ public class TimeOfDayConditionHandler extends BaseConditionModuleHandler implem
     /**
      * The start time of the user configured time span.
      */
-    private final LocalTime startTime;
+    private final @Nullable LocalTime startTime;
     /**
      * The end time of the user configured time span.
      */
-    private final LocalTime endTime;
+    private final @Nullable LocalTime endTime;
 
     public TimeOfDayConditionHandler(Condition condition) {
         super(condition);
@@ -67,6 +70,8 @@ public class TimeOfDayConditionHandler extends BaseConditionModuleHandler implem
 
     @Override
     public boolean isSatisfiedAt(ZonedDateTime time) {
+        LocalTime startTime = this.startTime;
+        LocalTime endTime = this.endTime;
         if (startTime == null || endTime == null) {
             logger.warn("Time condition with id {} is not well configured: startTime={}  endTime = {}", module.getId(),
                     startTime, endTime);

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/TimeOfDayTriggerHandler.java

@@ -14,6 +14,8 @@ package org.openhab.core.automation.internal.module.handler;
 
 import java.text.MessageFormat;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.ModuleHandlerCallback;
 import org.openhab.core.automation.Trigger;
 import org.openhab.core.automation.handler.BaseTriggerModuleHandler;
@@ -32,6 +34,7 @@ import org.slf4j.LoggerFactory;
  *
  * @author Kai Kreuzer - Initial contribution
  */
+@NonNullByDefault
 public class TimeOfDayTriggerHandler extends BaseTriggerModuleHandler
         implements SchedulerRunnable, TimeBasedTriggerHandler {
 
@@ -44,7 +47,7 @@ public class TimeOfDayTriggerHandler extends BaseTriggerModuleHandler
 
     private final CronScheduler scheduler;
     private final String expression;
-    private ScheduledCompletableFuture<?> schedule;
+    private @Nullable ScheduledCompletableFuture<?> schedule;
 
     public TimeOfDayTriggerHandler(Trigger module, CronScheduler scheduler) {
         super(module);
@@ -80,7 +83,7 @@ public class TimeOfDayTriggerHandler extends BaseTriggerModuleHandler
     @Override
     public void run() {
         if (callback != null) {
-            ((TriggerHandlerCallback) callback).triggered(module, null);
+            ((TriggerHandlerCallback) callback).triggered(module);
         } else {
             logger.debug("Tried to trigger, but callback isn't available!");
         }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/handler/TimerModuleHandlerFactory.java

@@ -15,6 +15,8 @@ package org.openhab.core.automation.internal.module.handler;
 import java.util.Arrays;
 import java.util.Collection;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Condition;
 import org.openhab.core.automation.Module;
 import org.openhab.core.automation.Trigger;
@@ -22,6 +24,7 @@ import org.openhab.core.automation.handler.BaseModuleHandlerFactory;
 import org.openhab.core.automation.handler.ModuleHandler;
 import org.openhab.core.automation.handler.ModuleHandlerFactory;
 import org.openhab.core.scheduler.CronScheduler;
+import org.osgi.service.component.annotations.Activate;
 import org.osgi.service.component.annotations.Component;
 import org.osgi.service.component.annotations.Deactivate;
 import org.osgi.service.component.annotations.Reference;
@@ -35,6 +38,7 @@ import org.slf4j.LoggerFactory;
  * @author Christoph Knauf - Initial contribution
  * @author Kai Kreuzer - added new module types
  */
+@NonNullByDefault
 @Component(immediate = true, service = ModuleHandlerFactory.class)
 public class TimerModuleHandlerFactory extends BaseModuleHandlerFactory {
 
@@ -45,7 +49,12 @@ public class TimerModuleHandlerFactory extends BaseModuleHandlerFactory {
             .asList(new String[] { GenericCronTriggerHandler.MODULE_TYPE_ID, TimeOfDayTriggerHandler.MODULE_TYPE_ID,
                     TimeOfDayConditionHandler.MODULE_TYPE_ID, DayOfWeekConditionHandler.MODULE_TYPE_ID });
 
-    private CronScheduler scheduler;
+    private final CronScheduler scheduler;
+
+    @Activate
+    public TimerModuleHandlerFactory(final @Reference CronScheduler scheduler) {
+        this.scheduler = scheduler;
+    }
 
     @Override
     @Deactivate
@@ -53,22 +62,13 @@ public class TimerModuleHandlerFactory extends BaseModuleHandlerFactory {
         super.deactivate();
     }
 
-    @Reference
-    protected void setCronScheduler(CronScheduler scheduler) {
-        this.scheduler = scheduler;
-    }
-
-    protected void unsetCronScheduler(CronScheduler scheduler) {
-        this.scheduler = null;
-    }
-
     @Override
     public Collection<String> getTypes() {
         return TYPES;
     }
 
     @Override
-    protected ModuleHandler internalCreate(Module module, String ruleUID) {
+    protected @Nullable ModuleHandler internalCreate(Module module, String ruleUID) {
         logger.trace("create {} -> {}", module.getId(), module.getTypeUID());
         String moduleTypeUID = module.getTypeUID();
         if (GenericCronTriggerHandler.MODULE_TYPE_ID.equals(moduleTypeUID) && module instanceof Trigger) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/module/provider/AnnotatedActionModuleTypeProvider.java

@@ -218,6 +218,9 @@ public class AnnotatedActionModuleTypeProvider extends BaseModuleHandlerFactory
                         false);
                 if (finalMI != null) {
                     ActionType moduleType = helper.buildModuleType(module.getTypeUID(), moduleInformation);
+                    if (moduleType == null) {
+                        return null;
+                    }
                     return new AnnotationActionHandler(actionModule, moduleType, finalMI.getMethod(),
                             finalMI.getActionProvider());
                 }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/parser/gson/ActionInstanceCreator.java

@@ -14,6 +14,7 @@ package org.openhab.core.automation.internal.parser.gson;
 
 import java.lang.reflect.Type;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.type.ActionType;
 import org.openhab.core.automation.type.CompositeActionType;
 
@@ -24,10 +25,11 @@ import com.google.gson.InstanceCreator;
  *
  * @author Ana Dimova - Initial contribution
  */
+@NonNullByDefault
 public class ActionInstanceCreator implements InstanceCreator<CompositeActionType> {
 
     @Override
-    public CompositeActionType createInstance(Type type) {
+    public CompositeActionType createInstance(@NonNullByDefault({}) Type type) {
         return new CompositeActionType(null, null, null, null, null);
     }
 }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/parser/gson/ConditionInstanceCreator.java

@@ -14,6 +14,7 @@ package org.openhab.core.automation.internal.parser.gson;
 
 import java.lang.reflect.Type;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.type.CompositeConditionType;
 import org.openhab.core.automation.type.ConditionType;
 
@@ -24,10 +25,11 @@ import com.google.gson.InstanceCreator;
  *
  * @author Ana Dimova - Initial contribution
  */
+@NonNullByDefault
 public class ConditionInstanceCreator implements InstanceCreator<CompositeConditionType> {
 
     @Override
-    public CompositeConditionType createInstance(Type type) {
+    public CompositeConditionType createInstance(@NonNullByDefault({}) Type type) {
         return new CompositeConditionType(null, null, null, null);
     }
 }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/parser/gson/ModuleTypeGSONParser.java

@@ -21,6 +21,8 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.dto.ActionTypeDTOMapper;
 import org.openhab.core.automation.dto.CompositeActionTypeDTO;
 import org.openhab.core.automation.dto.CompositeConditionTypeDTO;
@@ -42,6 +44,7 @@ import org.osgi.service.component.annotations.Component;
  *
  * @author Kai Kreuzer - Initial contribution
  */
+@NonNullByDefault
 @Component(immediate = true, service = Parser.class, property = { "parser.type=parser.module.type", "format=json" })
 public class ModuleTypeGSONParser extends AbstractGSONParser<ModuleType> {
 
@@ -68,7 +71,7 @@ public class ModuleTypeGSONParser extends AbstractGSONParser<ModuleType> {
         gson.toJson(map, writer);
     }
 
-    private void addAll(Set<ModuleType> result, List<? extends ModuleTypeDTO> moduleTypes) {
+    private void addAll(Set<ModuleType> result, @Nullable List<? extends ModuleTypeDTO> moduleTypes) {
         if (moduleTypes != null) {
             for (ModuleTypeDTO mt : moduleTypes) {
                 if (mt instanceof CompositeTriggerTypeDTO) {

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/parser/gson/ModuleTypeParsingContainer.java

@@ -14,6 +14,8 @@ package org.openhab.core.automation.internal.parser.gson;
 
 import java.util.List;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.dto.CompositeActionTypeDTO;
 import org.openhab.core.automation.dto.CompositeConditionTypeDTO;
 import org.openhab.core.automation.dto.CompositeTriggerTypeDTO;
@@ -24,11 +26,12 @@ import org.openhab.core.automation.dto.CompositeTriggerTypeDTO;
  *
  * @author Kai Kreuzer - Initial contribution
  */
+@NonNullByDefault
 public class ModuleTypeParsingContainer {
 
-    public List<CompositeTriggerTypeDTO> triggers;
+    public @Nullable List<CompositeTriggerTypeDTO> triggers;
 
-    public List<CompositeConditionTypeDTO> conditions;
+    public @Nullable List<CompositeConditionTypeDTO> conditions;
 
-    public List<CompositeActionTypeDTO> actions;
+    public @Nullable List<CompositeActionTypeDTO> actions;
 }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/parser/gson/TriggerInstanceCreator.java

@@ -14,6 +14,7 @@ package org.openhab.core.automation.internal.parser.gson;
 
 import java.lang.reflect.Type;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.type.CompositeTriggerType;
 import org.openhab.core.automation.type.TriggerType;
 
@@ -24,10 +25,11 @@ import com.google.gson.InstanceCreator;
  *
  * @author Ana Dimova - Initial contribution
  */
+@NonNullByDefault
 public class TriggerInstanceCreator implements InstanceCreator<CompositeTriggerType> {
 
     @Override
-    public CompositeTriggerType createInstance(Type type) {
+    public CompositeTriggerType createInstance(@NonNullByDefault({}) Type type) {
         return new CompositeTriggerType(null, null, null, null);
     }
 }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/provider/AutomationResourceBundlesEventQueue.java

@@ -18,6 +18,8 @@ import java.util.LinkedList;
 import java.util.List;
 
 import org.eclipse.jdt.annotation.NonNull;
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.automation.Rule;
 import org.openhab.core.automation.template.TemplateProvider;
 import org.openhab.core.automation.type.ModuleTypeProvider;
@@ -34,6 +36,7 @@ import org.slf4j.LoggerFactory;
  * @author Kai Kreuzer - refactored (managed) provider and registry implementation
  * @param <E>
  */
+@NonNullByDefault
 public class AutomationResourceBundlesEventQueue<@NonNull E> implements Runnable {
 
     /**
@@ -52,7 +55,7 @@ public class AutomationResourceBundlesEventQueue<@NonNull E> implements Runnable
      */
     private boolean running = false;
 
-    private Thread runningThread;
+    private @Nullable Thread runningThread;
 
     /**
      * This field is for synchronization purposes

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/provider/file/AutomationWatchService.java

@@ -19,6 +19,8 @@ import java.nio.file.Path;
 import java.nio.file.WatchEvent;
 import java.nio.file.WatchEvent.Kind;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.service.AbstractWatchService;
 
 /**
@@ -30,6 +32,7 @@ import org.openhab.core.service.AbstractWatchService;
  * @author Ana Dimova - Initial contribution
  */
 @SuppressWarnings("rawtypes")
+@NonNullByDefault
 public class AutomationWatchService extends AbstractWatchService {
 
     private AbstractFileProvider provider;
@@ -45,7 +48,7 @@ public class AutomationWatchService extends AbstractWatchService {
     }
 
     @Override
-    protected Kind<?>[] getWatchEventKinds(Path subDir) {
+    protected Kind<?> @Nullable [] getWatchEventKinds(Path subDir) {
         return new Kind<?>[] { ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY };
     }
 

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/provider/file/TemplateFileProviderWatcher.java

@@ -14,6 +14,7 @@ package org.openhab.core.automation.internal.provider.file;
 
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.openhab.core.automation.parser.Parser;
 import org.openhab.core.automation.template.RuleTemplate;
 import org.openhab.core.automation.template.RuleTemplateProvider;
@@ -28,6 +29,7 @@ import org.osgi.service.component.annotations.ReferencePolicy;
  *
  * @author Ana Dimova - Initial contribution
  */
+@NonNullByDefault
 @Component(immediate = true, service = RuleTemplateProvider.class)
 public class TemplateFileProviderWatcher extends TemplateFileProvider {
 

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/internal/provider/file/WatchServiceUtil.java

@@ -13,15 +13,19 @@
 package org.openhab.core.automation.internal.provider.file;
 
 import java.io.File;
+import java.nio.file.Path;
 import java.util.HashMap;
 import java.util.Map;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+
 /**
  * This class isolates the java 1.7 functionality which tracks the file system changes.
  *
  * @author Ana Dimova - Initial contribution
  */
 @SuppressWarnings("rawtypes")
+@NonNullByDefault
 public class WatchServiceUtil {
 
     private static final Map<AbstractFileProvider, Map<String, AutomationWatchService>> WATCH_SERVICES = new HashMap<>();
@@ -46,17 +50,22 @@ public class WatchServiceUtil {
     }
 
     public static void deactivateWatchService(String watchingDir, AbstractFileProvider provider) {
-        AutomationWatchService aws;
+        AutomationWatchService aws = null;
         synchronized (WATCH_SERVICES) {
             Map<String, AutomationWatchService> watchers = WATCH_SERVICES.get(provider);
+            if (watchers != null) {
                 aws = watchers.remove(watchingDir);
                 if (watchers.isEmpty()) {
                     WATCH_SERVICES.remove(provider);
                 }
             }
+        }
         if (aws != null) {
             aws.deactivate();
-            provider.removeResources(aws.getSourcePath().toFile());
+            Path sourcePath = aws.getSourcePath();
+            if (sourcePath != null) {
+                provider.removeResources(sourcePath.toFile());
+            }
         }
     }
 }

bundles/org.openhab.core.automation/src/main/java/org/openhab/core/automation/thingsupport/AnnotatedThingActionModuleTypeProvider.java

@@ -235,6 +235,9 @@ public class AnnotatedThingActionModuleTypeProvider extends BaseModuleHandlerFac
                         true);
                 if (finalMI != null) {
                     ActionType moduleType = helper.buildModuleType(module.getTypeUID(), moduleInformation);
+                    if (moduleType == null) {
+                        return null;
+                    }
                     return new AnnotationActionHandler(actionModule, moduleType, finalMI.getMethod(),
                             finalMI.getActionProvider());
                 }

bundles/org.openhab.core.automation/src/test/java/org/openhab/core/automation/internal/module/handler/ItemStateConditionHandlerTest.java

@@ -238,8 +238,6 @@ public class ItemStateConditionHandlerTest {
                 .withId("conditionId") //
                 .withTypeUID(ItemStateConditionHandler.ITEM_STATE_CONDITION) //
                 .withConfiguration(configuration);
-        ItemStateConditionHandler handler = new ItemStateConditionHandler(builder.build());
+        return new ItemStateConditionHandler(builder.build(), mockItemRegistry);
-        handler.setItemRegistry(mockItemRegistry);
-        return handler;
     }
 }

bundles/org.openhab.core/src/main/java/org/openhab/core/library/dimension/ArealDensity.java

@@ -14,11 +14,14 @@ package org.openhab.core.library.dimension;
 
 import javax.measure.Quantity;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+
 /**
  * Define Area density type (basic unit is kg/m^2)
  * https://en.wikipedia.org/wiki/Area_density
  *
  * @author Gaël L'hopital - Initial contribution
  */
+@NonNullByDefault
 public interface ArealDensity extends Quantity<ArealDensity> {
 }

bundles/org.openhab.core/src/main/java/org/openhab/core/library/dimension/Density.java

@@ -14,10 +14,13 @@ package org.openhab.core.library.dimension;
 
 import javax.measure.Quantity;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+
 /**
  * Define Density type (basic unit is kg/m^3)
  *
  * @author Jan N. Klug - Initial contribution
  */
+@NonNullByDefault
 public interface Density extends Quantity<Density> {
 }

bundles/org.openhab.core/src/main/java/org/openhab/core/library/dimension/Intensity.java

@@ -14,11 +14,14 @@ package org.openhab.core.library.dimension;
 
 import javax.measure.Quantity;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+
 /**
  * This interface represents the intensity dimension.
  *
  * @author Henning Treu - Initial contribution
  */
+@NonNullByDefault
 public interface Intensity extends Quantity<Intensity> {
 
 }

bundles/org.openhab.core/src/main/java/org/openhab/core/library/dimension/VolumetricFlowRate.java

@@ -14,10 +14,13 @@ package org.openhab.core.library.dimension;
 
 import javax.measure.Quantity;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+
 /**
  * Define Volumetric Flow Rate type (basic unit is m^3/s).
  *
  * @author Łukasz Dywicki - Initial contribution
  */
+@NonNullByDefault
 public interface VolumetricFlowRate extends Quantity<VolumetricFlowRate> {
 }