When initiating a SAML authentication request (from the Service Provider), is there any way to give the Identity Provider a hint as to which username to use? In my application I know which user it wants to authenticate (based on a unique link the user clicked in an e-mail), and I'd like that username to be prefilled in the IdP's username box.
Using SAML 2.0 with Active Directory Federation Services (AD FS) 2.1.