Add @Nullable to Object#equals()

This is a partial cherry-pick of change:
I5eedb571c9d78862115dfdc5dae1cf2a35343580

for connectivity classes.

Bug: 170883422
Test: m
Merged-In: I5eedb571c9d78862115dfdc5dae1cf2a35343580
Change-Id: I7dc661863b73f4198ddb4f3a1566583d0f07db3c
11 files changed
tree: 013a34b14433078122fe11bc267839ffe51dd4a3
  1. core/
  2. framework/
  3. service/
  4. services/
  5. tests/
  6. OWNERS