@Override
  public String toString() {
    // Add details on maintenance event.
    StringBuilder sb = new StringBuilder();
    sb.append(String.format("{Handling %s", _maintenanceEventType));
    if (_topicsWithRFUpdate != null) {
      // Add summary for TOPIC_REPLICATION_FACTOR
      sb.append(String.format(" by desired RF: [%s]", _topicsWithRFUpdate));
    } else if (_brokers != null) {
      // Add summary for ADD_BROKER / REMOVE_BROKER / DEMOTE_BROKER
      sb.append(String.format(" for brokers: [%s]", _brokers));
    }
    sb.append("}");
    return sb.toString();
  }
@Test
  public void testToStringBeforeConfiguration() {
    assertNotNull(new MaintenanceEvent().toString());
  }