@Override
    public void callGroup(ConfigurationRequest request,
                          StreamObserver<GroupConfigurationResponse> responseObserver) {
        GroupConfigurationResponse response;
        String uuid = request.getUuid();
        switch (this.dataFlag.get()) {
            case 1:
                response = GroupConfigurationResponse
                    .newBuilder().setUuid(UUID.randomUUID().toString())
                    .addGroupConfigTable(GroupConfigItems
                                             .newBuilder().setGroupName("test-module.grpc.testKeyGroup")
                                             .addItems(Config
                                                           .newBuilder()
                                                           .setName("item1")
                                                           .setValue("100")
                                                           .build())
                                             .addItems(Config
                                                           .newBuilder()
                                                           .setName("item2")
                                                           .setValue("2000")
                                                           .build()).build()).build();
                responseObserver.onNext(response);
                break;
            case 2:
                response = GroupConfigurationResponse.newBuilder().setUuid(uuid).build();
                responseObserver.onNext(response);
                break;
            case 3:
                response = GroupConfigurationResponse
                    .newBuilder().setUuid(UUID.randomUUID().toString())
                    .addGroupConfigTable(GroupConfigItems
                                             .newBuilder().setGroupName("test-module.grpc.testKeyGroup")
                                             .addItems(Config
                                                           .newBuilder()
                                                           .setName("item2")
                                                           .setValue("2000")
                                                           .build()).build()).build();
                responseObserver.onNext(response);
                break;
            default:
                response = GroupConfigurationResponse
                    .newBuilder().setUuid(UUID.randomUUID().toString())
                    .addGroupConfigTable(GroupConfigItems
                                             .newBuilder().setGroupName("test-module.grpc.testKeyGroup")
                                             .addItems(Config
                                                           .newBuilder()
                                                           .setName("item1")
                                                           .setValue("100")
                                                           .build())
                                             .addItems(Config
                                                           .newBuilder()
                                                           .setName("item2")
                                                           .setValue("200")
                                                           .build()).build()).build();
                responseObserver.onNext(response);
        }
        responseObserver.onCompleted();
    }
@param dataFlag 0:init, 1:change, 2:no change, 3:delete
oap-server/server-configuration/grpc-configuration-sync/src/test/java/org/apache/skywalking/oap/server/configuration/grpc/MockGRPCConfigService.java