Adding new Attribute Interfaces to java-api.

[Tom Zeller]

> I'm intending following Scott's lead and adding Interfaces in front of the
> major attribute functionality
>
> - AttributeFilter
> - AttributeDefinition
> - DataConnectorDefinition
> - AttributeResolver
>
> (Attribute mapping is already behind an interface)
>
> In most cases the Interface would collect most of the methods and inherit
> the name currently used by the definition.  The definition would then become
> BaseXXXX (or, if not abstract ConcreteXXX - unless anyone has a better name
> for this case)
>
> The motivation is to provide another, very high level plugin point for
> people who need that level of control.  I'm just firing a mail in here to
> test whether anyone thinks this is a bad idea and to ask whether anyone has
> a preference for whether the interfaces should go in idp-attribute-api, or
> into the appropriate idp-attribute-*-api module?

Interfaces for those objects were explicitly removed in v3, reversing
warrants a review of that fundamental design choice. So, no, I am not
in favor at the moment because the original author specifically did
not do so.