That's a new finding for me.
What I do normally is to download the SSL certificate from internet browser such as IE. After that I will add the SSL certificate that I downloaded to my application's truststore. This way has worked many and many times before and has never gone wrong.
However, unfortunately this time the above method did not work anymore. I then troubleshooted the application by enabling the Java SSL Debug mode by adding the JVM parameter "-Djavax.net.debug=ssl" so that my application would print out the SSL debug information to the STDOUT. From there I spotted this line "certificate_unknown", then I further confirmed the CN details of the SSL certificate received by my application from the Web Service Provider is different that the one that I've added to my application's truststore.
Next I chose to retrieve the SSL certificate by using openssl. I installed OpenSSL for Windows , then ran the following command "openssl s_client -connect host:port" to fetch the SSL certificate details. I saved the details as a CER file, then added that CER to my truststore and hooray my SSL handshake issue is gone!