Code Review Request, JDK-8228757 : Fail fast if the handshake type is unknown

[Xuelei Fan]

Hi,

Could I have the following code cleanup reviewed?

    http://cr.openjdk.java.net/~xuelei/8228757/webrev.00/

It is trying to fail fast if unknown handshake type get requested. 
Simple fix and hard to capture the fail point, no new regression test.

Thanks,
Xuelei