My usecase is to make parallel calls in Js.I can achieve the same using Javascript but my backends need the SSL info to be configured.
I have seen use case request more than once before.
But long story short - It looks like what you are asking is not supported through JS as of today.However there could be one option worth trying to make it work - node.js. You might be aware that you can run node.js as a target in Apigee and you might want to try it using node.js - http://nategood.com/nodejs-ssl-client-cert-auth-api-rest @Diego Zuluaga might be able to share some insights
This is a thread you might want to refer on a similar topic - https://community.apigee.com/questions/1749/is-it-possible-to-configure-ssl-information-using.html
Agreed @Vinit Mehta. Here's also a good snippet from Trireme git repo and some context about how it's handled on Edge.