OIF 11.1.1.5: How do I pass Query String Parameters to Unsolicited Relay State?

Hello,

Background:

IdP initiated SSO , HTTP Post Profile, SAML 2.0

Problem:

It seems that the Federation Engine is dropping query string parameters specified in the "Unsolicited Relay State" or speified via the "returnurl" when posting SAML Payload at the Assertion Consumer Service URL at SP.

We are attempting to deep link into specific functionality on the SP side that we can get to by issuing following type of query: returnurl=https://example.com?param1=value1&param2=value2

In the above example, the federation engine seems to be dropping query string parameters param1=value1&param2=value2

Thanks.