Fixing @Beta tags

Change-Id: I93a3be9a81a8f29f7b1ce29b66f09c9bcd31e639
diff --git a/incubator/api/src/main/java/org/onosproject/incubator/net/intf/InterfaceService.java b/incubator/api/src/main/java/org/onosproject/incubator/net/intf/InterfaceService.java
index ad1bf34..b164df9 100644
--- a/incubator/api/src/main/java/org/onosproject/incubator/net/intf/InterfaceService.java
+++ b/incubator/api/src/main/java/org/onosproject/incubator/net/intf/InterfaceService.java
@@ -16,6 +16,7 @@
 
 package org.onosproject.incubator.net.intf;
 
+import com.google.common.annotations.Beta;
 import org.onlab.packet.IpAddress;
 import org.onlab.packet.VlanId;
 import org.onosproject.net.ConnectPoint;
@@ -25,6 +26,7 @@
 /**
  * Service for interacting with interfaces.
  */
+@Beta
 public interface InterfaceService {
 
     /**