public static void refreshSuperUserGroupsConfiguration() {
    //load server side configuration;
    refreshSuperUserGroupsConfiguration(new Configuration());
  }
@Test
  public void testProxyUsersWithCustomPrefix() throws Exception {
    Configuration conf = new Configuration(false);
    conf.set("x." + REAL_USER_NAME + ".users",
        StringUtils.join(",", Arrays.asList(AUTHORIZED_PROXY_USER_NAME)));
    conf.set("x." + REAL_USER_NAME+ ".hosts", PROXY_IP);
    ProxyUsers.refreshSuperUserGroupsConfiguration(conf, "x");


    // First try proxying a user that's allowed
    UserGroupInformation realUserUgi = UserGroupInformation
        .createRemoteUser(REAL_USER_NAME);
    UserGroupInformation proxyUserUgi = UserGroupInformation.createProxyUserForTesting(
        AUTHORIZED_PROXY_USER_NAME, realUserUgi, GROUP_NAMES);

    // From good IP
    assertAuthorized(proxyUserUgi, "1.2.3.4");
    // From bad IP
    assertNotAuthorized(proxyUserUgi, "1.2.3.5");

    // Now try proxying a user that's not allowed
    realUserUgi = UserGroupInformation.createRemoteUser(REAL_USER_NAME);
    proxyUserUgi = UserGroupInformation.createProxyUserForTesting(
        PROXY_USER_NAME, realUserUgi, GROUP_NAMES);

    // From good IP
    assertNotAuthorized(proxyUserUgi, "1.2.3.4");
    // From bad IP
    assertNotAuthorized(proxyUserUgi, "1.2.3.5");
  }