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

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

Change-Id: Ibd342970b8e2b3d7bbb9cb6521de2d06843b5427
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>