public void start() throws IOException {
    shuttingDown = false;
    startServerThread();
    handler.init(this);
  }
After constructing a TcpServer use this method to start its server-socket listening thread.
A TcpServer should be stopped via a ShutdownRequest made through a TcpClient.

@see TcpClient#stop(HostAndPort)
geode-tcp-server/src/main/java/org/apache/geode/distributed/internal/tcpserver/TcpServer.java