[ONOS-6687] Add ApplicationRole enum type in protobuf model

Change-Id: I10919eeffbc57f6ca75a58e4c6a3ceecff780f1f
diff --git a/incubator/protobuf/models/src/main/proto/app/ApplicationEnumsProto.proto b/incubator/protobuf/models/src/main/proto/app/ApplicationEnumsProto.proto
index a61e046..4815561 100644
--- a/incubator/protobuf/models/src/main/proto/app/ApplicationEnumsProto.proto
+++ b/incubator/protobuf/models/src/main/proto/app/ApplicationEnumsProto.proto
@@ -8,4 +8,15 @@
     INSTALLED = 0;
     // Indicates that application is active.
     ACTIVE = 1;
-}
\ No newline at end of file
+}
+
+enum ApplicationRoleProto {
+    // Indicates that an application has an ADMIN role.
+    ADMIN = 0;
+    // Indicates that an application has a USER role.
+    USER = 1;
+    // Indicates that an application role has not been specified.
+    UNSPECIFIED = 2;
+
+    // More useful roles may be defined...
+}