The error message you’ve posted is usually a sign that the certificate used in the TLS connection is either self-signed or that the certificate authority (CA) isn’t known to Java, that the CA is not included in your JVM’s trust store.
Please refer to the following article for one possible solution: http://www.mkyong.com/webservices/jax-ws/suncertpathbuilderexception-unable-to-find-valid-certification-path-to-requested-target/