[ONOS-7683] Add unit tests for a set of telemetry config classes

Change-Id: I73ad36e02044371a2fb87540e28ef2257a6dba92
diff --git a/apps/openstacktelemetry/api/src/main/java/org/onosproject/openstacktelemetry/api/config/GrpcTelemetryConfig.java b/apps/openstacktelemetry/api/src/main/java/org/onosproject/openstacktelemetry/api/config/GrpcTelemetryConfig.java
index 56a364e..d7c8f62 100644
--- a/apps/openstacktelemetry/api/src/main/java/org/onosproject/openstacktelemetry/api/config/GrpcTelemetryConfig.java
+++ b/apps/openstacktelemetry/api/src/main/java/org/onosproject/openstacktelemetry/api/config/GrpcTelemetryConfig.java
@@ -20,7 +20,7 @@
 /**
  * Configuration API of gRPC for publishing openstack telemetry.
  */
-public interface GrpcTelemetryConfig {
+public interface GrpcTelemetryConfig extends TelemetryConfig {
 
     /**
      * Obtains gRPC server IP address.
@@ -60,7 +60,7 @@
     /**
      * Builder class of GrpcTelemetryConfig.
      */
-    interface Builder {
+    interface Builder extends TelemetryConfig.Builder {
 
         /**
          * Sets gRPC server IP address.