Merge "Add nullable annotation" into udc-qpr-dev am: 31679166a7

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/24544468

Change-Id: Ifd6ac159f610f6a9a3a0f409778a6084f411949f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>