As of now the constants retrieved from a nested class - usually an enum - will be fed to the combine-strategy in a manner that expects the combine-strategy to include one constant from each enum in each callback-record. This ~API~ seems to fit most situations very well but there should perhaps be ways to instruct the combine-strategy to populate the callback-records with a certain number of constants from a certain enum. Such as having some of the produced callback-records contain two or three of the enum's constants while some other callback-records contain no constant of the particular enum.
I think it would be unwise to be too hasty about this. We should not have a rash API included in the distribution and then later find out there are smarter or more elegant ways to accomplish the same thing. Let's instead have this feature-request link to similar ones and make a more informed decision based on actual needs and a wide collection of different API suggestions.
