Made ResourceManager to accept arbitrary ResourceConsumer implementation. (ONOS-4406)

Change-Id: If41564824770c2a8b78237a206c036df94141117
diff --git a/core/api/src/main/java/org/onosproject/net/resource/ResourceConsumer.java b/core/api/src/main/java/org/onosproject/net/resource/ResourceConsumer.java
index c9d5691..f4b0e11 100644
--- a/core/api/src/main/java/org/onosproject/net/resource/ResourceConsumer.java
+++ b/core/api/src/main/java/org/onosproject/net/resource/ResourceConsumer.java
@@ -22,4 +22,10 @@
  */
 @Beta
 public interface ResourceConsumer {
+    /**
+     * Returns ID of this consumer.
+     *
+     * @return ID of this consumer
+     */
+    ResourceConsumerId consumerId();
 }