Summary:
For collections whose type does not express that the collection is thread-safe (e.g., `Collections.syncrhonizedMap` and friends).
If you annotate a field holding one of these collections, we won't warn when you mutate the collection.
Reviewed By: jeremydubreil
Differential Revision: D4763565
fbshipit-source-id: 58b487a
Sam Blackshear