question: @ Override public synchronized void addHandshakeCompletedListener ( HandshakeCompletedListener listener ) { if ( listener == null ) { throw new IllegalArgumentException ( "listener is null" ) ; } if ( handshakeListeners == null ) { handshakeListeners = new HashMap < HandshakeCompletedListener , AccessControlContext > ( 4 ) ; } handshakeListeners . put ( listener , AccessController . getContext ( ) ) ; }
target:  Registers an event listener to receive notifications that an SSL handshake has completed on this connection.