Fix errorprone warnings that should be errors am: 27db4326e4 am: 24d17c9351 am: 628a5b25a0

Original change: https://android-review.googlesource.com/c/platform/packages/apps/DocumentsUI/+/2256451

Change-Id: I87f3a1cbfba0ab738c53be3100711fa0b63514f7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>