If you are suffering from the dreaded message
PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
and you have installed the necessary certificates in your keystore.
to your java runtime. You will now get *a lot* of details about the keystore which is used, the certificates which are available and the SSL negotiation.
This should help to figure out what exactly is going wrong (like a hostname match problem or problem caused by SNI or something else).