CAMEL-21306: camel-jsonpath - Null should be accepted return value

components/camel-jsonpath/src/main/java/org/apache/camel/jsonpath/JsonPathEngine.java

@@ -194,15 +194,15 @@ private Object doRead(String path, Exchange exchange) throws IOException, CamelE
         if (json instanceof String) {
             LOG.trace("JSonPath: {} is read as String: {}", path, json);
             String str = (String) json;
-            answer = JsonPath.using(configuration).parse(str).read(path);
+            return JsonPath.using(configuration).parse(str).read(path);
         } else if (json instanceof Map) {
             LOG.trace("JSonPath: {} is read as Map: {}", path, json);
             Map map = (Map) json;
-            answer = JsonPath.using(configuration).parse(map).read(path);
+            return JsonPath.using(configuration).parse(map).read(path);
         } else if (json instanceof List) {
             LOG.trace("JSonPath: {} is read as List: {}", path, json);
             List list = (List) json;
-            answer = JsonPath.using(configuration).parse(list).read(path);
+            return JsonPath.using(configuration).parse(list).read(path);
         } else {
             //try to auto convert into inputStream
             answer = readWithInputStream(path, exchange);

components/camel-jsonpath/src/test/java/org/apache/camel/jsonpath/JsonPathNullHeaderTest.java

@@ -0,0 +1,64 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.camel.jsonpath;
+
+import org.apache.camel.builder.RouteBuilder;
+import org.apache.camel.component.mock.MockEndpoint;
+import org.apache.camel.test.junit5.CamelTestSupport;
+import org.junit.jupiter.api.Test;
+
+public class JsonPathNullHeaderTest extends CamelTestSupport {
+
+    @Override
+    protected RouteBuilder createRouteBuilder() {
+        return new RouteBuilder() {
+            @Override
+            public void configure() {
+                from("direct:start")
+                        .setHeader("foo").jsonpath("$.foo")
+                        .to("mock:foo");
+            }
+        };
+    }
+
+    @Test
+    public void testHeaderValue() throws Exception {
+        getMockEndpoint("mock:foo").expectedHeaderReceived("foo", "cheese");
+
+        template.sendBody("direct:start", """
+                {
+                  "foo": "cheese"
+                }
+                """);
+
+        MockEndpoint.assertIsSatisfied(context);
+    }
+
+    @Test
+    public void testHeaderNull() throws Exception {
+        getMockEndpoint("mock:foo").expectedHeaderReceived("foo", null);
+
+        template.sendBody("direct:start", """
+                {
+                  "foo": null
+                }
+                """);
+
+        MockEndpoint.assertIsSatisfied(context);
+    }
+
+}