Commented Feature: Allow constraining an attribute route [1255]

When trying to constrain an attribute route based on the incoming request, I could not find a way to do it other than an inline request with a fake parameter.

This will work in some cases (but not for example for a catch all route).

I suggest we allow passing constraints (not inlineconstraint or httpbuilder) right at attribute level.
Comments: We should also allow the same behavior for a regular route