From 4afe1511085b6617582549b9d207c7b7aff61b3e Mon Sep 17 00:00:00 2001
From: J-N-K <github@klug.nrw>
Date: Sun, 23 Jul 2023 17:14:16 +0200
Subject: [PATCH] [jsonpath] Fix exception when input string is empty (#15283)

Signed-off-by: Jan N. Klug <github@klug.nrw>
---
 .../jsonpath/internal/JSonPathTransformationService.java      | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/bundles/org.openhab.transform.jsonpath/src/main/java/org/openhab/transform/jsonpath/internal/JSonPathTransformationService.java b/bundles/org.openhab.transform.jsonpath/src/main/java/org/openhab/transform/jsonpath/internal/JSonPathTransformationService.java
index 91939afa968..a38bf650324 100644
--- a/bundles/org.openhab.transform.jsonpath/src/main/java/org/openhab/transform/jsonpath/internal/JSonPathTransformationService.java
+++ b/bundles/org.openhab.transform.jsonpath/src/main/java/org/openhab/transform/jsonpath/internal/JSonPathTransformationService.java
@@ -59,6 +59,10 @@ public class JSonPathTransformationService implements TransformationService {
 
         logger.debug("about to transform '{}' by the function '{}'", source, jsonPathExpression);
 
+        if (source.isBlank()) {
+            // return null if source is empty/blank, JSONPath will throw an IAE on empty input strings
+            return null;
+        }
         try {
             Object transformationResult = JsonPath.read(source, jsonPathExpression);
             logger.debug("transformation resulted in '{}'", transformationResult);