Replace com.android.internal.util.Preconditions.checkNotNull with

java.util.Objects.requireNonNull

Removing variable self assignments. This wasn't an issue with
checNotNull because of difference in input and output types, but
requireNonNull doesn't add any attributes.

Bug: 126528330

Test: Treehugger
Change-Id: I6dc5c489ceec1f118bf7f3c21c3206f0b4477f70