Modify MPLS/VLAN query

- ONOS-3507 VlanQuery to return available VLAN IDs
- ONOS-3508 MplsQuery to return available MPLS Labels
- Advertise that VLAN and MPLS resources are available on OVS

Change-Id: I74cd05393c8919b4823d0666348008adb93c9290
diff --git a/core/api/src/main/java/org/onosproject/net/behaviour/VlanQuery.java b/core/api/src/main/java/org/onosproject/net/behaviour/VlanQuery.java
index a1057c9..ce313f8 100644
--- a/core/api/src/main/java/org/onosproject/net/behaviour/VlanQuery.java
+++ b/core/api/src/main/java/org/onosproject/net/behaviour/VlanQuery.java
@@ -16,6 +16,9 @@
 package org.onosproject.net.behaviour;
 
 import com.google.common.annotations.Beta;
+
+import java.util.Set;
+import org.onlab.packet.VlanId;
 import org.onosproject.net.PortNumber;
 import org.onosproject.net.driver.HandlerBehaviour;
 
@@ -26,10 +29,11 @@
 public interface VlanQuery extends HandlerBehaviour {
 
     /**
-     * Indicates if VLAN can be used at the port.
+     * Returns set of VlanIds which can be used at the port.
      *
-     * @param port port to be checked for the capability
-     * @return true if VLAN can be used at the port, false otherwise.
+     * @param port to be checked for the available resources.
+     * @return Set of VlanIds which can be used at the port.
      */
-    boolean isEnabled(PortNumber port);
+    Set<VlanId> queryVlanIds(PortNumber port);
+
 }