Refactor: add javadoc, restrict visibility, etc for sona switching

Change-Id: I9f5d8e53fb037a34f31dc15f9038a8fd0e756356
diff --git a/apps/openstacknetworking/api/src/main/java/org/onosproject/openstacknetworking/api/InstancePortEvent.java b/apps/openstacknetworking/api/src/main/java/org/onosproject/openstacknetworking/api/InstancePortEvent.java
index 547e41f..00f15ed 100644
--- a/apps/openstacknetworking/api/src/main/java/org/onosproject/openstacknetworking/api/InstancePortEvent.java
+++ b/apps/openstacknetworking/api/src/main/java/org/onosproject/openstacknetworking/api/InstancePortEvent.java
@@ -22,6 +22,9 @@
  */
 public class InstancePortEvent extends AbstractEvent<InstancePortEvent.Type, InstancePort> {
 
+    /**
+     * Instance port event type.
+     */
     public enum Type {
 
         /**