Google Generates Warning: Relay state exceeds 80 bytes, some application may not support this.

[Peter Schober]

Completely unrelated to that thread but anyway:

* Ullfig, Roberto <rullfig at uic.edu> [2013-10-18 15:57]:
> <!-- Google Apps -->
> <!-- Do not release transientID to google.com - things break -->
>     <afp:AttributeFilterPolicy id="google.com">
>         <afp:PolicyRequirementRule xsi:type="basic:AttributeRequesterString" value="google.com" />
>         <afp:AttributeRule attributeID="principal"> <afp:PermitValueRule xsi:type="basic:ANY" /> </afp:AttributeRule>
>     </afp:AttributeFilterPolicy>
> 
> We've commented out the releaseTransientIdToAnyone policy and
> explicitly release transientID in all other policies. Other SP
> logins do not generate this message.

I'd turn that around and add a DenyValueRule to the google SP for
transientIds, and re-enable the releaseTransientIdToAnyone rule.
Safes you adding transients to every other SP.

Or look at "IdP Name Identifier Selection Process" at the end of
https://wiki.shibboleth.net/confluence/display/SHIB2/IdPNameIdentifier
-peter