@SuppressWarnings("JavaReflectionMemberAccess")
  private TcpClient getLegacyTcpClient()
      throws NoSuchMethodException, IllegalAccessException, InvocationTargetException,
      InstantiationException {
    final Constructor<TcpClient> constructor = TcpClient.class.getConstructor(Properties.class);
    return constructor.newInstance(getDistributedSystemProperties());
  }
The TcpClient class changed in version FIRST_NEW_VERSION. That version (and later)
no longer has the old constructor TcpClient(final Properties), so we have to access
that constructor via reflection.
geode-tcp-server/src/upgradeTest/java/org/apache/geode/distributed/internal/tcpserver/TcpServerProductVersionUpgradeTest.java