In my application I use 3rd party library (Spring Data for MongoDB to be exact).
Methods of this library return Iterable, while the rest of my
IteratorUtils from commons-collections may help (although they don't support generics in the latest stable version 3.2.1):
@SuppressWarnings("unchecked")
Collection list = IteratorUtils.toList(iterable.iterator());
Version 4.0 (which is in SNAPSHOT at this moment) supports generics and you can get rid of the @SuppressWarnings.
Update: Check IterableAsList from Cactoos.