Fixing @Beta tags

Change-Id: I93a3be9a81a8f29f7b1ce29b66f09c9bcd31e639
diff --git a/core/api/src/main/java/org/onosproject/security/AppGuard.java b/core/api/src/main/java/org/onosproject/security/AppGuard.java
index 800135f..4b80dfc 100644
--- a/core/api/src/main/java/org/onosproject/security/AppGuard.java
+++ b/core/api/src/main/java/org/onosproject/security/AppGuard.java
@@ -17,9 +17,12 @@
 package org.onosproject.security;
 
 
+import com.google.common.annotations.Beta;
+
 /**
  * Aids SM-ONOS to perform API-level permission checking.
  */
+@Beta
 public final class AppGuard {
 
     private AppGuard() {