In order to implement VOLTHA VOL-949 task (https://jira.opencord.org/browse/VOL-949) , OltPipeline (pmc-olt driver) must support meter, transition and also QinQ vlan push instructions.

Change-Id: Ie027469fa190a78b0c8366da55431ebc62e699ef
diff --git a/core/net/src/main/java/org/onosproject/net/meter/impl/MeterManager.java b/core/net/src/main/java/org/onosproject/net/meter/impl/MeterManager.java
index 11420a9..f6f4816 100644
--- a/core/net/src/main/java/org/onosproject/net/meter/impl/MeterManager.java
+++ b/core/net/src/main/java/org/onosproject/net/meter/impl/MeterManager.java
@@ -375,6 +375,10 @@
                     log.info("Meter removed {}", event.subject());
                     post(new MeterEvent(MeterEvent.Type.METER_REMOVED, event.subject()));
                     break;
+                case METER_REFERENCE_COUNT_ZERO:
+                    log.info("Meter reference count zero {}", event.subject());
+                    post(new MeterEvent(MeterEvent.Type.METER_REFERENCE_COUNT_ZERO, event.subject()));
+                    break;
                 default:
                     log.warn("Unknown meter event {}", event.type());
             }