Specifying that a close_notify alert is sent when one is received

If the jdk.tls.acknowledgeCloseNotify system property is set to true, when the client or server receives a close_notify alert, it sends a corresponding close_notify alert and the connection is duplex-closed.

TLS 1.2 and earlier versions use a duplex-close policy. However, TLS 1.3 uses a half-close policy, which means that the inbound and outbound close_notify alerts are independent. When upgrading to TLS 1.3, unexpected behavior can occur if your application shuts down the TLS connection by using only one of the SSLEngine.closeInbound() or SSLEngine.closeOutbound() methods but not both on each side of the connection. If your application unexpectedly hangs or times out when the underlying TLS transportation is not duplex-closed, you might need to set this property to true.