@Override
    public Principal authenticate(Properties props, DistributedMember member)
        throws AuthenticationFailedException {
      System.out
          .println(Thread.currentThread().getName() + ": TestPeerAuthenticator authenticating "
              + member + " at " + System.currentTimeMillis());

      // Get the user name and password
      String userName = props.getProperty(USER_NAME);
      String password = props.getProperty(PASSWORD);

      // If they are not equal, throw an exception
      if (!userName.equals(password)) {
        String msg = "Invalid user name and password combination supplied for user " + userName;
        throw new AuthenticationFailedException(msg);
      }
      return new TestPrincipal(userName);
    }
Use of SECURITY_CLIENT_AUTHENTICATOR should result in the servers performing authentication
during HandShake of Gateway Sender/Receiver connecting.
geode-wan/src/distributedTest/java/org/apache/geode/internal/cache/wan/GatewayLegacyAuthenticationRegressionTest.java