Guava's `Collections2` and `Iterables` doesn't have any methods that return Predicate, so I think `CollectionGuavas` is the wrong place for this stuff. If it's in a class like `XyzPredicates` then it'll be a lot clearer that the methods return predicates. Same for returning a Supplier (it's not obvious from the name it'll do that). Also not keen on the name CollectionGuavas.