Feature request: add partition method to Sets utility class

The utility class Sets could use a new method <T> Set<Set<T>> partition(Set<T> set, int size), similar to the one in Lists class. Such a method would be useful for various applications, e.g. for batch processing elements for which order is unspecified/unimportant, and I don’t think there is a straightforward way of achieving the same effect with Java 8 streams API.

[cpovirk]

Another complication: Iterables.partition can be done in a “mostly streaming” fashion, but Sets.partition would need to be done eagerly (or else inefficiently). That means that switching from Iterables.partition to Sets.partition has performance implications – different (IIRC) from comparable switches like from Iterables.filter to Sets.filter.

[lowasser]

I’m not sure why you wouldn’t write

Iterables.partition(elements, batchSize)
    .forEach(batch -> processElements(new HashSet<>(batch)))

I’m also a bit concerned about issues like Sets.partition(myTreeSet, batchSize) not being able to identify which set implementation to use. It’s not even clear what set implementation we’d want – immutable? LinkedHashSet? – where there’s no real ambiguity for lists.