[automerger skipped] Merge "Fixes more @Nullable issues in System UI and...

[automerger skipped] Merge "Fixes more  @Nullable issues in System UI and WMShell." into udc-qpr-dev-plus-aosp am: a20959a0 -s ours

am skip reason: Merged-In Ibd2b0163b47571da5f276f09ce5dcfd875f09a1c with SHA-1 10c09e60 is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/24589269



Change-Id: I6b68a27114ceaf0c8f372b1a06f666c63e8af102
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>