fix concurrent modification of remote instances.

module/dal/remote/src/main/java/org/openbase/bco/dal/remote/action/RemoteAction.java

@@ -56,6 +56,7 @@
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.*;
 
@@ -73,7 +74,7 @@ public class RemoteAction implements Action {
     private final ActionParameter actionParameter;
     private final ObservableImpl<RemoteAction, ActionDescription> actionDescriptionObservable;
     private final AuthToken authToken;
-    private final List<RemoteAction> impactedRemoteActions = new ArrayList<>();
+    private final List<RemoteAction> impactedRemoteActions = Collections.synchronizedList(new ArrayList<>());
     private final Observer impactActionObserver = new Observer<RemoteAction, ActionDescription>() {
         @Override
         public void update(RemoteAction source, ActionDescription observable) throws Exception {