Make resource retrieval more efficient when specifing resource type

This resolves ONOS-4666

Change-Id: I9d09b60531ca48b36fc20f43498cda62f1badb8b
diff --git a/core/store/dist/src/main/java/org/onosproject/store/resource/impl/ConsistentResourceStore.java b/core/store/dist/src/main/java/org/onosproject/store/resource/impl/ConsistentResourceStore.java
index 69645b1..0ecc108 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/resource/impl/ConsistentResourceStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/resource/impl/ConsistentResourceStore.java
@@ -296,6 +296,17 @@
                 .build();
     }
 
+    @Override
+    public <T> Set<Resource> getChildResources(DiscreteResourceId parent, Class<T> cls) {
+        checkNotNull(parent);
+        checkNotNull(cls);
+
+        return ImmutableSet.<Resource>builder()
+                .addAll(discreteStore.getChildResources(parent, cls))
+                .addAll(continuousStore.getChildResources(parent, cls))
+                .build();
+    }
+
     // computational complexity: O(n) where n is the number of the children of the parent
     @Override
     public <T> Collection<Resource> getAllocatedResources(DiscreteResourceId parent, Class<T> cls) {