Merge "Explicitly mention a confusing proto3 infelicity." into main am: 3a0c095253 am: b76d6fd9b1

Original change: https://android-review.googlesource.com/c/platform/system/core/+/3531073

Change-Id: Ib9297819fe815c06142e6dd4a9fc61a5b71e353d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>