setFilter
Adds @filter as an authentication filter to @domain.
The filter gets a chance to bypass authentication for certain requests that would otherwise require it. Eg, it might check the message's path in some way that is too complicated to do via the other methods, or it might check the message's method, and allow GETs but not PUTs.
The filter function returns true if the request should still require authentication, or false if authentication is unnecessary for this request.
To help prevent security holes, your filter should return true by default, and only return false under specifically-tested circumstances, rather than the other way around. Eg, in the example above, where you want to authenticate PUTs but not GETs, you should check if the method is GET and return false in that case, and then return true for all other methods (rather than returning true for PUT and false for all other methods). This way if it turned out (now or later) that some paths supported additional methods besides GET and PUT, those methods would default to being NOT allowed for unauthenticated users.
You can also set the filter by setting the SoupAuthDomain:filter and property@AuthDomain:filter-data properties, which can also be used to set the filter at construct time.
Parameters
the auth filter for @domain