Merge "Add some more public doc for MacAddress" am: a9a005de38

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1354447

Change-Id: I1126b78eb886c5c84afa107b028fe2569d7573e4
tree: 8cd4b37d51edfe319a966d09182443b5702bf327
  1. core/
  2. services/
  3. tests/