The certificate for the site is fine so you don't need to disable certificate validation. But, the site requires the use of Server Name Indication (SNI) to present the correct certificate. If SNI is supported depends and if it is enabled depends on the Java version, but it is not available with Java 1.6 and lower.
Apart from that the Handshake Exception might indicate that the problem is not related to certificate validation at all. The site only supports a few ciphers which all use AES256. But support for AES256 is not available in Java by default because of export restrictions.