Summary:
mityal implemented a new check for nullsafe to warn about potentially
incorrect overrides of `equals` method (not yet released).
While testing some other things I stumbled upon incorrect `equal`
overrides in Flipper, particularly not properly handling `null` param.
Reviewed By: passy
Differential Revision: D19639882
fbshipit-source-id: 7f9aec7270e89a906810807f6849628967047b2a