Merge "Mark DataUsageState as nullable to avoid potential NPE risk" am: 0960af0bf3 am: 325b033f85 am: 8c4db8e545

Original change: https://android-review.googlesource.com/c/platform/packages/apps/Settings/+/2217422

Change-Id: Ic87c58e6eb59b154258a97ff54c0e5295637af12
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>