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

Change-Id: I73ad36e02044371a2fb87540e28ef2257a6dba92
diff --git a/apps/openstacktelemetry/app/src/main/java/org/onosproject/openstacktelemetry/config/DefaultInfluxDbTelemetryConfig.java b/apps/openstacktelemetry/app/src/main/java/org/onosproject/openstacktelemetry/config/DefaultInfluxDbTelemetryConfig.java
index a95517b..68b28c1 100644
--- a/apps/openstacktelemetry/app/src/main/java/org/onosproject/openstacktelemetry/config/DefaultInfluxDbTelemetryConfig.java
+++ b/apps/openstacktelemetry/app/src/main/java/org/onosproject/openstacktelemetry/config/DefaultInfluxDbTelemetryConfig.java
@@ -18,6 +18,7 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Maps;
 import org.onosproject.openstacktelemetry.api.config.InfluxDbTelemetryConfig;
+import org.onosproject.openstacktelemetry.api.config.TelemetryConfig;
 
 import java.util.Map;
 import java.util.Objects;
@@ -113,10 +114,15 @@
         return Objects.hash(address, port, username, password, database, enableBatch, configMap);
     }
 
+    @Override
+    public TelemetryConfig.Builder createBuilder() {
+        return new DefaultBuilder();
+    }
+
     /**
      * Builder class of DefaultInfluxDbTelemetryConfig.
      */
-    public final class DefaultBuilder implements Builder {
+    public static final class DefaultBuilder implements Builder {
 
         private String address;
         private int port;