@Override
  protected void init() throws ServiceException {
    Configuration hConf = new Configuration(false);
    ConfigurationUtils.copy(getServiceConfig(), hConf);
    hGroups = new org.apache.hadoop.security.Groups(hConf);
  }
@Test(expected = RuntimeException.class)
  @TestDir
  public void invalidGroupsMapping() throws Exception {
    String dir = TestDirHelper.getTestDir().getAbsolutePath();
    Configuration conf = new Configuration(false);
    conf.set("server.services", StringUtils.join(",", Arrays.asList(GroupsService.class.getName())));
    conf.set("server.groups.hadoop.security.group.mapping", String.class.getName());
    Server server = new Server("server", dir, dir, dir, dir, conf);
    server.init();
  }