this class is using internall and not public Java api from SUN via sun.security.util.HostnameChecker
this is not a good idea and practice as this API is not supported at all by Oracle
see http://www.oracle.com/technetwork/java/faq-sun-packages-142232.html
We know about this recommended practice and decided against it. Maybe look up the code comments and the implemented use to follow the reasoning.