Basic support for joins in OData v2

It's half a bug, half a feature request
We deal with a perticular OData almost v2 server that uses system functions disguised as entitities. Basically, "/A('b')/C" works but not "/C?$filter=foo eq 'b'". In order to have that, we've enabled the joins support on the ODataTranslator, but we still haven't the right query generated. We've traced back the origin to the optimizer:

• SELECT * FROM a join b ON a.x=b.y WHERE a.x='v'
• is optimized as SELECT <columns> FROM a join b ON a.x=b.y WHERE a.x='v' AND b.y='v'

The extra induced condition "b.y = 'v'" messes up with the URL construction. Any idea about how to proceed from there?