Keep resolveConfig in sync (#5776)

Signed-off-by: Leo Siepel <leosiepel@gmail.com>

Author: lsiepel

bundles/org.openhab.core.thing/src/main/java/org/openhab/core/thing/binding/BaseThingHandler.java

@@ -157,6 +157,19 @@ public Thing getThing() {
     @Override
     public void thingUpdated(Thing thing) {
         dispose();
+        setThing(thing);
+        initialize();
+    }
+
+    /**
+     * Replaces the {@link Thing} handled by this handler and refreshes its resolved configuration.
+     * <p>
+     * Custom {@link #thingUpdated(Thing)} implementations should use this method instead of assigning directly to
+     * {@link #thing}, so the Thing and resolved configuration remain consistent.
+     *
+     * @param thing the updated Thing
+     */
+    protected final void setThing(Thing thing) {
         Configuration resolvedConfiguration;
         try {
             resolvedConfiguration = ConfigUtil.resolveVariables(thing.getConfiguration());
@@ -169,7 +182,6 @@ public void thingUpdated(Thing thing) {
             this.thing = thing;
             this.resolvedConfig = resolvedConfiguration;
         }
-        initialize();
     }
 
     @Override

bundles/org.openhab.core.thing/src/test/java/org/openhab/core/thing/binding/BaseThingHandlerTest.java

@@ -66,6 +66,10 @@ public void handleCommand(ChannelUID channelUID, Command command) {
         public void initialize() {
             this.configInInitialize = getConfig();
         }
+
+        public void replaceThing(Thing thing) {
+            setThing(thing);
+        }
     }
 
     private static class ConfigUtilAccessor extends ConfigUtil {
@@ -124,6 +128,18 @@ public void testResolvedConfigAfterThingUpdate() {
         assertEquals("resolved-bar", handler.getConfig().get("p2"));
     }
 
+    @Test
+    public void testResolvedConfigAfterSetThing() {
+        handler.getConfig();
+        Thing thing = handler.editThing()
+                .withConfiguration(new Configuration(Map.of("p1", "${ENV:FOO}", "p2", "${ENV:BAR}"))).build();
+
+        handler.replaceThing(thing);
+
+        assertEquals("resolved-foo", handler.getConfig().get("p1"));
+        assertEquals("resolved-bar", handler.getConfig().get("p2"));
+    }
+
     @Test
     public void testResolvedConfigAfterUpdateThing() {
         // Action: Update the Thing with new configuration