Merge "Nullability check for wait module." am: e1df179f00 am: cea7551a27

Original change: https://android-review.googlesource.com/c/platform/bionic/+/2539233

Change-Id: Ia8f48d9701a4eed83418091e02dde6ce3124eace
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>