Bruno’s answer was the correct one in the end. This is most easily controlled by the https.protocols
system property. This is how you are able to control what the factory method returns. Set to “TLSv1” for example.
It seems that in the debug log for Java 6
the request is send in SSLv2
format.
main, WRITE: SSLv2 client hello message, length = 110
This is not mentioned as enabled by default in Java 7.
Change the client to use SSLv3 and above to avoid such interoperability issues.