diff --git a/bundles/org.openhab.core.automation.module.script/src/main/java/org/openhab/core/automation/module/script/internal/defaultscope/ScriptThingActions.java b/bundles/org.openhab.core.automation.module.script/src/main/java/org/openhab/core/automation/module/script/internal/defaultscope/ScriptThingActions.java
index c9fa0d303..28d4b8be8 100644
--- a/bundles/org.openhab.core.automation.module.script/src/main/java/org/openhab/core/automation/module/script/internal/defaultscope/ScriptThingActions.java
+++ b/bundles/org.openhab.core.automation.module.script/src/main/java/org/openhab/core/automation/module/script/internal/defaultscope/ScriptThingActions.java
@@ -21,9 +21,6 @@ import org.openhab.core.thing.ThingUID;
 import org.openhab.core.thing.binding.ThingActions;
 import org.openhab.core.thing.binding.ThingActionsScope;
 import org.openhab.core.thing.binding.ThingHandler;
-import org.osgi.service.component.annotations.Reference;
-import org.osgi.service.component.annotations.ReferenceCardinality;
-import org.osgi.service.component.annotations.ReferencePolicy;
 
 /**
  * The methods of this class are made available as functions in the scripts.
@@ -35,13 +32,12 @@ import org.osgi.service.component.annotations.ReferencePolicy;
 public class ScriptThingActions {
 
     private static final Map<String, ThingActions> THING_ACTIONS_MAP = new HashMap<>();
+    private ThingRegistry thingRegistry;
 
     ScriptThingActions(ThingRegistry thingRegistry) {
         this.thingRegistry = thingRegistry;
     }
 
-    private ThingRegistry thingRegistry;
-
     public void dispose() {
         this.thingRegistry = null;
     }
@@ -67,7 +63,6 @@ public class ScriptThingActions {
         return null;
     }
 
-    @Reference(policy = ReferencePolicy.DYNAMIC, cardinality = ReferenceCardinality.MULTIPLE)
     void addThingActions(ThingActions thingActions) {
         String key = getKey(thingActions);
         THING_ACTIONS_MAP.put(key, thingActions);
diff --git a/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/ScriptServiceUtil.java b/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/ScriptServiceUtil.java
index 7f1a998a0..164a6b4b8 100644
--- a/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/ScriptServiceUtil.java
+++ b/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/ScriptServiceUtil.java
@@ -18,11 +18,11 @@ import java.util.concurrent.atomic.AtomicReference;
 
 import org.openhab.core.events.EventPublisher;
 import org.openhab.core.items.ItemRegistry;
-import org.openhab.core.thing.ThingRegistry;
-import org.openhab.core.thing.binding.ThingActions;
 import org.openhab.core.model.core.ModelRepository;
 import org.openhab.core.model.script.engine.ScriptEngine;
 import org.openhab.core.model.script.engine.action.ActionService;
+import org.openhab.core.thing.ThingRegistry;
+import org.openhab.core.thing.binding.ThingActions;
 import org.osgi.service.component.annotations.Activate;
 import org.osgi.service.component.annotations.Component;
 import org.osgi.service.component.annotations.Deactivate;
diff --git a/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/internal/engine/action/ThingActionService.java b/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/internal/engine/action/ThingActionService.java
index f4f62f2e7..1fba6016c 100644
--- a/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/internal/engine/action/ThingActionService.java
+++ b/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/internal/engine/action/ThingActionService.java
@@ -15,6 +15,8 @@ package org.openhab.core.model.script.internal.engine.action;
 import java.util.HashMap;
 import java.util.Map;
 
+import org.openhab.core.model.script.actions.Things;
+import org.openhab.core.model.script.engine.action.ActionService;
 import org.openhab.core.thing.Thing;
 import org.openhab.core.thing.ThingRegistry;
 import org.openhab.core.thing.ThingStatusInfo;
@@ -22,8 +24,7 @@ import org.openhab.core.thing.ThingUID;
 import org.openhab.core.thing.binding.ThingActions;
 import org.openhab.core.thing.binding.ThingActionsScope;
 import org.openhab.core.thing.binding.ThingHandler;
-import org.openhab.core.model.script.actions.Things;
-import org.openhab.core.model.script.engine.action.ActionService;
+import org.osgi.service.component.annotations.Activate;
 import org.osgi.service.component.annotations.Component;
 import org.osgi.service.component.annotations.Reference;
 import org.osgi.service.component.annotations.ReferenceCardinality;
@@ -38,23 +39,19 @@ import org.osgi.service.component.annotations.ReferencePolicy;
 @Component(immediate = true)
 public class ThingActionService implements ActionService {
 
+    private static final Map<String, ThingActions> THING_ACTIONS_MAP = new HashMap<>();
     private static ThingRegistry thingRegistry;
-    private static final Map<String, ThingActions> thingActionsMap = new HashMap<>();
+
+    @Activate
+    public ThingActionService(final @Reference ThingRegistry thingRegistry) {
+        ThingActionService.thingRegistry = thingRegistry;
+    }
 
     @Override
     public Class<?> getActionClass() {
         return Things.class;
     }
 
-    @Reference
-    public void setThingRegistry(ThingRegistry thingRegistry) {
-        ThingActionService.thingRegistry = thingRegistry;
-    }
-
-    public void unsetThingRegistry(ThingRegistry thingRegistry) {
-        ThingActionService.thingRegistry = null;
-    }
-
     public static ThingStatusInfo getThingStatusInfo(String thingUid) {
         ThingUID uid = new ThingUID(thingUid);
         Thing thing = thingRegistry.get(uid);
@@ -66,13 +63,21 @@ public class ThingActionService implements ActionService {
         }
     }
 
+    /**
+     * Gets an actions instance of a certain scope for a given thing UID
+     *
+     * @param scope the action scope
+     * @param thingUid the UID of the thing
+     *
+     * @return actions the actions instance or null, if not available
+     */
     public static ThingActions getActions(String scope, String thingUid) {
         ThingUID uid = new ThingUID(thingUid);
         Thing thing = thingRegistry.get(uid);
         if (thing != null) {
             ThingHandler handler = thing.getHandler();
             if (handler != null) {
-                ThingActions thingActions = thingActionsMap.get(getKey(scope, thingUid));
+                ThingActions thingActions = THING_ACTIONS_MAP.get(getKey(scope, thingUid));
                 return thingActions;
             }
         }
@@ -82,12 +87,12 @@ public class ThingActionService implements ActionService {
     @Reference(policy = ReferencePolicy.DYNAMIC, cardinality = ReferenceCardinality.MULTIPLE)
     public void addThingActions(ThingActions thingActions) {
         String key = getKey(thingActions);
-        thingActionsMap.put(key, thingActions);
+        THING_ACTIONS_MAP.put(key, thingActions);
     }
 
     public void removeThingActions(ThingActions thingActions) {
         String key = getKey(thingActions);
-        thingActionsMap.remove(key);
+        THING_ACTIONS_MAP.remove(key);
     }
 
     private static String getKey(ThingActions thingActions) {
@@ -108,4 +113,5 @@ public class ThingActionService implements ActionService {
         ThingActionsScope scopeAnnotation = actions.getClass().getAnnotation(ThingActionsScope.class);
         return scopeAnnotation.name();
     }
+
 }
diff --git a/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/scoping/ActionClassLoader.java b/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/scoping/ActionClassLoader.java
index 41d277a67..b2c39f860 100644
--- a/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/scoping/ActionClassLoader.java
+++ b/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/scoping/ActionClassLoader.java
@@ -12,9 +12,9 @@
  */
 package org.openhab.core.model.script.scoping;
 
-import org.openhab.core.thing.binding.ThingActions;
 import org.openhab.core.model.script.ScriptServiceUtil;
 import org.openhab.core.model.script.engine.action.ActionService;
+import org.openhab.core.thing.binding.ThingActions;
 
 /**
  * This is a special class loader that tries to resolve classes from available {@link ActionService}s,
diff --git a/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/scoping/ScriptImplicitlyImportedTypes.java b/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/scoping/ScriptImplicitlyImportedTypes.java
index fc28c38b4..c77150fb5 100644
--- a/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/scoping/ScriptImplicitlyImportedTypes.java
+++ b/bundles/org.openhab.core.model.script/src/org/openhab/core/model/script/scoping/ScriptImplicitlyImportedTypes.java
@@ -19,12 +19,13 @@ import java.util.ArrayList;
 import java.util.List;
 
 import org.apache.commons.lang.StringUtils;
+import org.eclipse.xtext.xbase.scoping.batch.ImplicitlyImportedFeatures;
+import org.joda.time.DateTime;
 import org.openhab.core.library.unit.BinaryPrefix;
 import org.openhab.core.library.unit.ImperialUnits;
 import org.openhab.core.library.unit.MetricPrefix;
 import org.openhab.core.library.unit.SIUnits;
 import org.openhab.core.library.unit.SmartHomeUnits;
-import org.openhab.core.thing.binding.ThingActions;
 import org.openhab.core.model.persistence.extensions.PersistenceExtensions;
 import org.openhab.core.model.script.actions.Audio;
 import org.openhab.core.model.script.actions.BusEvent;
@@ -39,8 +40,7 @@ import org.openhab.core.model.script.engine.IActionServiceProvider;
 import org.openhab.core.model.script.engine.IThingActionsProvider;
 import org.openhab.core.model.script.engine.action.ActionService;
 import org.openhab.core.model.script.lib.NumberExtensions;
-import org.eclipse.xtext.xbase.scoping.batch.ImplicitlyImportedFeatures;
-import org.joda.time.DateTime;
+import org.openhab.core.thing.binding.ThingActions;
 
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
@@ -53,7 +53,6 @@ import com.google.inject.Singleton;
  * @author Kai Kreuzer - Initial contribution
  * @author Oliver Libutzki - Xtext 2.5.0 migration
  */
-@SuppressWarnings("restriction")
 @Singleton
 public class ScriptImplicitlyImportedTypes extends ImplicitlyImportedFeatures {
 
diff --git a/bundles/org.openhab.core.thing/src/main/java/org/openhab/core/thing/binding/ThingActions.java b/bundles/org.openhab.core.thing/src/main/java/org/openhab/core/thing/binding/ThingActions.java
index 670b53aa3..5dc7d2c5e 100644
--- a/bundles/org.openhab.core.thing/src/main/java/org/openhab/core/thing/binding/ThingActions.java
+++ b/bundles/org.openhab.core.thing/src/main/java/org/openhab/core/thing/binding/ThingActions.java
@@ -12,11 +12,14 @@
  */
 package org.openhab.core.thing.binding;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+
 /**
- * Marker interface for Automation Actions with access to a ThingHandler
+ * Marker interface for Automation Actions with access to a {@link ThingHandler}.
  *
  * @author Stefan Triller - Initial contribution
  */
+@NonNullByDefault
 public interface ThingActions extends ThingHandlerService {
 
 }
diff --git a/bundles/org.openhab.core.thing/src/main/java/org/openhab/core/thing/binding/ThingHandlerService.java b/bundles/org.openhab.core.thing/src/main/java/org/openhab/core/thing/binding/ThingHandlerService.java
index e2de19486..e1c1f79a2 100644
--- a/bundles/org.openhab.core.thing/src/main/java/org/openhab/core/thing/binding/ThingHandlerService.java
+++ b/bundles/org.openhab.core.thing/src/main/java/org/openhab/core/thing/binding/ThingHandlerService.java
@@ -12,12 +12,16 @@
  */
 package org.openhab.core.thing.binding;
 
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+
 /**
  *
- * Interface for a service that provides access to a {@link ThingHandler}
+ * Interface for a service that provides access to a {@link ThingHandler}.
  *
  * @author Stefan Triller - Initial contribution
  */
+@NonNullByDefault
 public interface ThingHandlerService {
 
     /**
@@ -32,6 +36,7 @@ public interface ThingHandlerService {
      *
      * @return the {@link ThingHandler}
      */
+    @Nullable
     ThingHandler getThingHandler();
 
     /**