IdP v3.2 is stripping Query parameters

[Priyanshu Bhalotia]

Hello,
I am using spring security saml 2 and i have overriden HTTPPostEncoder
on my SP side and i am appending a query parameter in IdP HTTP POST
URL Endpoint. The URL is being requested in the browser but then the
custom parameter is being removed and my query parameter is lost at
IdP login page.

Sample scenario

1. i open https://sp.example.com on browser
2. it gets redirected (with my parameters q1=value1) to
https://idp.example.com/idp/profile/SAML2/POST/SSO?q1=value1
3. The url that renders login page is
https://idp.example.com/idp/profile/SAML2/POST/SSO?execution=e5s1
with my custom query parameters getting removed.

How can I receive the sent parameter at IdP endpoint, so that I can
use this info on login page url.

--
Priyanshu Bhalotia