private TcpClient getTcpClient() {

    SocketCreatorFactory
        .setDistributionConfig(new DistributionConfigImpl(getDistributedSystemProperties()));

    return new TcpClient(
        SocketCreatorFactory
            .getSocketCreatorForComponent(SecurableCommunicationChannel.LOCATOR),
        InternalDataSerializer.getDSFIDSerializer().getObjectSerializer(),
        InternalDataSerializer.getDSFIDSerializer().getObjectDeserializer(),
        TcpSocketFactory.DEFAULT);
  }
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