OGM-414 Early feedback

@DavideD, @emmanuelbernard: This is not ready yet, but can you give me quick feedback on a specific question (see in-line comment below).
> it seems to make sense, what problems it might cause to add a generic?

Not real problems, more that I was wondering whether it pulls its weight if only used in two methods of the interface. Having a separate contract around queries might change it.

> I conceptually like Davide's idea of moving it to a dedicated contract. I think we did that for some other sub space no?

I'll play with it. I think last time we discussed it you didn't like it :) But I think it'd make sense.