Returns the default SSL server socket factory.
The first time this method is called, the security property "ssl.ServerSocketFactory.provider" is examined. If it is non-null, a class by that name is loaded and instantiated. If that is successful and the object is an instance of SSLServerSocketFactory, it is made the default SSL server socket factory.
Otherwise, this method returns
SSLContext.getDefault().getServerSocketFactory(). If that
call fails, an inoperative factory is returned.