Gateway filter on post

[Dom]

I have a gateway authentication filter in place. 

I post a form to the controller that the gateway filter intercepts, and 
does the redirect. 

No TGC cookie is found and I'm redirected again.
But post becomes a get!  

Have I missed something in the configuration. 

Is this a bug or have I stretch the gateway authenticaton filter.

I suppose I could do some all posts to a different url mapping, but that 
seems weird. 



I'll try and do a text sequence diagram. Sorry if this looks like crap!

browser   filter   controller   cas
 |--------->|POST      |         | 
 |<---------|REDIRECT 2|CAS      |
 |----------|----------|-------->|hasCOOKIE?
 |<---------|----------|---------|NO COOKIE,
 |--------->|GATEWAYED |         |REDIRECT TO SERVICE
 |          |--------->|         |
 |          |          |-------->|REDIRECT IS NOW
 |<---------|----------|---------|POST