Merge "Lock down String8.isEmpty() usage" into main am: 358a982b71 am: b19c86cdd3 am: 1263ea0299 am: 457c96513d am: 7fae10db2c

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2705824

Change-Id: I966f868c80a53ba384c328e87cd00ce499b86e28
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>