[VOL-936] add changes for onu distance from OLT

Change-Id: If6201799946ac753780d0424c4bd986e2fb394d2
diff --git a/common/core/northbound/grpc/default_api_handler.go b/common/core/northbound/grpc/default_api_handler.go
index 3c38459..a350bc3 100644
--- a/common/core/northbound/grpc/default_api_handler.go
+++ b/common/core/northbound/grpc/default_api_handler.go
@@ -386,3 +386,7 @@
 func (handler *DefaultAPIHandler) StartOmciTestAction(ctx context.Context, omcitestrequest *voltha.OmciTestRequest) (*voltha.TestResponse, error) {
 	return nil, errors.New("StartOmciTestAction-unimplemented")
 }
+func (handler *DefaultAPIHandler) GetExtValue(ctx context.Context, values *voltha.ValueSpecifier) (*voltha.ReturnValues, error) {
+	log.Debugw("GetExtValue-unimplemented", log.Fields{"onuid": values.Id})
+	return nil, nil
+}