e759b44c45
`checkNotNull` was added to the `Object` variant in b83f12c4ba. It
doesn't seem to have caused any test failures, so I guess we never
pass `null` in here - and might as well update the annotation to match
reality. And then for consistency we should ban `null` from the
`byte[]` overload too.
PiperOrigin-RevId: 628419003