Merge "Add some more @Nullable annotations" into sc-v2-dev am: e65c47e60f am: 228f1ef97b

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/16279499

Change-Id: I8352ede8e477bd22c61d3987f99d8d2c5b8a8012