Whether to allow half-open connections.
A half-open connection occurs when one end of the connection has called close() or sent a FIN packet, while the other end remains open. When set to true:
The socket won't automatically send FIN when the remote side closes its endThe local side can continue sending data even after the remote side has closedThe application must explicitly call end() to fully close the connectionWhen false, the socket automatically closes both ends of the connection when either side closes.