@Override
  public void close(boolean keepAlive) throws Exception {
    throw new UnsupportedOperationException(
        "Subscription connections should only be closed by subscription manager");
  }
A wrapper that holds a client to server connection and a server to client connection.

The clientToServerConnection should not be used outside of this class.
geode-core/src/main/java/org/apache/geode/cache/client/internal/QueueConnectionImpl.java