private static final String NUMBER_OF_NODES = "number_of_nodes";
    private static final String NUMBER_OF_DATA_NODES = "number_of_data_nodes";
    private static final String NUMBER_OF_PENDING_TASKS = "number_of_pending_tasks";
    private static final String NUMBER_OF_IN_FLIGHT_FETCH = "number_of_in_flight_fetch";
    private static final String DELAYED_UNASSIGNED_SHARDS = "delayed_unassigned_shards";

        assertTrue(mockConfig.getApiPingEsFieldSet().contains("delayed_unassigned_shards"));
        assertTrue(mockConfig.getApiPingEsFieldSet().contains("number_of_pending_tasks"));
        assertTrue(mockConfig.getApiPingEsFieldSet().contains("number_of_in_flight_fetch"));
        assertTrue(mockConfig.getApiPingEsFieldSet().contains("task_max_waiting_in_queue_millis"));