Add resource API to query registered resource

Change-Id: Ibf53a0fa383043d17e78578093eb3055631796d0

@@ -162,6 +162,15 @@ public interface ResourceService extends ListenerService<ResourceEvent, Resource
     Collection<Resource> getAvailableResources(Resource parent);
 
     /**
+     * Returns resources registered under the specified resource.
+     *
+     * @param parent parent resource
+     * @return registered resources under the specified resource
+     */
+    Collection<Resource> getRegisteredResources(Resource parent);
+
+
+    /**
      * Returns the availability of the specified resource.
      *
      * @param resource resource to check the availability

@@ -158,6 +158,13 @@ public final class ResourceManager extends AbstractListenerManager<ResourceEvent
     }
 
     @Override
+    public Collection<Resource> getRegisteredResources(Resource parent) {
+        checkNotNull(parent);
+
+        return store.getChildResources(parent);
+    }
+
+    @Override
     public boolean isAvailable(Resource resource) {
         checkNotNull(resource);
 

@@ -101,6 +101,11 @@ class MockResourceService implements ResourceService {
     }
 
     @Override
+    public Collection<Resource> getRegisteredResources(Resource parent) {
+        return getAvailableResources(parent);
+    }
+
+    @Override
     public boolean isAvailable(Resource resource) {
         return true;
     }