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