[dmx] Workaround for thing actions bug

bundles/org.openhab.binding.dmx/src/main/java/org/openhab/binding/dmx/action/DmxActions.java

@@ -12,6 +12,9 @@
  */
 package org.openhab.binding.dmx.action;
 
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+
 import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.eclipse.jdt.annotation.Nullable;
 import org.eclipse.smarthome.core.thing.binding.ThingActions;
@@ -25,20 +28,26 @@
 
 /**
  * The {@link DmxActions} provides actions for DMX Bridges
+ * <p>
+ * <b>Note:</b>The static method <b>invokeMethodOf</b> handles the case where
+ * the test <i>actions instanceof DmxActions</i> fails. This test can fail
+ * due to an issue in openHAB core v2.5.0 where the {@link DmxActions} class
+ * can be loaded by a different classloader than the <i>actions</i> instance.
  *
  * @author Jan N. Klug - Initial contribution
  */
 
 @ThingActionsScope(name = "dmx")
 @NonNullByDefault
-public class DmxActions implements ThingActions {
+public class DmxActions implements ThingActions, IDmxActions {
 
     private final Logger logger = LoggerFactory.getLogger(DmxActions.class);
 
     private @Nullable DmxBridgeHandler handler;
 
+    @Override
     @RuleAction(label = "DMX Output", description = "immediately performs fade on selected DMX channels")
-    void sendFade(@ActionInput(name = "channels") @Nullable String channels,
+    public void sendFade(@ActionInput(name = "channels") @Nullable String channels,
             @ActionInput(name = "fade") @Nullable String fade,
             @ActionInput(name = "resumeAfter") @Nullable Boolean resumeAfter) {
         logger.debug("thingHandlerAction called with inputs: {} {} {}", channels, fade, resumeAfter);
@@ -68,11 +77,26 @@ void sendFade(@ActionInput(name = "channels") @Nullable String channels,
 
     public static void sendFade(@Nullable ThingActions actions, @Nullable String channels, @Nullable String fade,
             @Nullable Boolean resumeAfter) {
-        if (actions instanceof DmxActions) {
-            ((DmxActions) actions).sendFade(channels, fade, resumeAfter);
-        } else {
-            throw new IllegalArgumentException("Instance is not an DmxActions class.");
+        invokeMethodOf(actions).sendFade(channels, fade, resumeAfter);
+    }
+
+    private static IDmxActions invokeMethodOf(@Nullable ThingActions actions) {
+        if (actions == null) {
+            throw new IllegalArgumentException("actions cannot be null");
+        }
+        if (actions.getClass().getName().equals(DmxActions.class.getName())) {
+            if (actions instanceof IDmxActions) {
+                return (IDmxActions) actions;
+            } else {
+                return (IDmxActions) Proxy.newProxyInstance(IDmxActions.class.getClassLoader(),
+                        new Class[] { IDmxActions.class }, (Object proxy, Method method, Object[] args) -> {
+                            Method m = actions.getClass().getDeclaredMethod(method.getName(),
+                                    method.getParameterTypes());
+                            return m.invoke(actions, args);
+                        });
+            }
         }
+        throw new IllegalArgumentException("Actions is not an instance of DmxActions");
     }
 
     @Override

bundles/org.openhab.binding.dmx/src/main/java/org/openhab/binding/dmx/action/IDmxActions.java

@@ -0,0 +1,27 @@
+/**
+ * Copyright (c) 2010-2020 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.binding.dmx.action;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+
+/**
+ * The {@link IDmxActions} defines the actions for DMX Bridges
+ *
+ * @author Laurent Garnier - Initial contribution
+ */
+@NonNullByDefault
+public interface IDmxActions {
+
+    public void sendFade(@Nullable String channels, @Nullable String fade, @Nullable Boolean resumeAfter);
+}