Refactor: specify the generic type for protobuf enum translator

Change-Id: I5a1df0cc2ab2372b68d5851b7b2a449c5d958bfe
diff --git a/incubator/protobuf/models/src/main/java/org/onosproject/incubator/protobuf/models/core/ApplicationEnumsProtoTranslator.java b/incubator/protobuf/models/src/main/java/org/onosproject/incubator/protobuf/models/core/ApplicationEnumsProtoTranslator.java
index d82f93e..6fe0319 100644
--- a/incubator/protobuf/models/src/main/java/org/onosproject/incubator/protobuf/models/core/ApplicationEnumsProtoTranslator.java
+++ b/incubator/protobuf/models/src/main/java/org/onosproject/incubator/protobuf/models/core/ApplicationEnumsProtoTranslator.java
@@ -59,7 +59,7 @@
      * @param roleProto gRPC message
      * @return {@link ApplicationRole}
      */
-    public static Optional<Object> translate(ApplicationRoleProto roleProto) {
+    public static Optional<ApplicationRole> translate(ApplicationRoleProto roleProto) {
 
         switch (roleProto) {
             case USER:
@@ -101,7 +101,7 @@
      * @param stateProto gRPC message
      * @return {@link ApplicationState}
      */
-    public static Optional<Object> translate(ApplicationStateProto stateProto) {
+    public static Optional<ApplicationState> translate(ApplicationStateProto stateProto) {
 
         switch (stateProto) {
             case ACTIVE:
diff --git a/incubator/protobuf/models/src/main/java/org/onosproject/incubator/protobuf/models/core/ApplicationProtoTranslator.java b/incubator/protobuf/models/src/main/java/org/onosproject/incubator/protobuf/models/core/ApplicationProtoTranslator.java
index 568be18..25a95e4 100644
--- a/incubator/protobuf/models/src/main/java/org/onosproject/incubator/protobuf/models/core/ApplicationProtoTranslator.java
+++ b/incubator/protobuf/models/src/main/java/org/onosproject/incubator/protobuf/models/core/ApplicationProtoTranslator.java
@@ -17,7 +17,6 @@
 
 import com.google.common.collect.Sets;
 import org.onosproject.core.Application;
-import org.onosproject.core.ApplicationRole;
 import org.onosproject.core.DefaultApplication;
 import org.onosproject.grpc.core.models.ApplicationProtoOuterClass.ApplicationProto;
 import org.onosproject.incubator.protobuf.models.security.PermissionProtoTranslator;
@@ -57,7 +56,7 @@
                 .withUrl(app.getUrl())
                 .withReadme(app.getReadme())
                 .withIcon(app.toByteArray())
-                .withRole((ApplicationRole) ApplicationEnumsProtoTranslator.translate(app.getRole()).get())
+                .withRole(ApplicationEnumsProtoTranslator.translate(app.getRole()).get())
                 .withPermissions(permissions)
                 .withFeatures(app.getFeaturesList())
                 .withFeaturesRepo(Optional.empty()) // TODO: need to add features repo