@Deprecated(forRemoval = true) // Remove in or after Openfire 5.1.0
    default void onConnectionClose( Object handback ) {}
Called when a connection is being closed.

@param handback The handback object associated with the connection listener during Connection.registerCloseListener()
@deprecated replaced by {@link #onConnectionClosing(Object)}
xmppserver/src/main/java/org/jivesoftware/openfire/ConnectionCloseListener.java