Merge "Improve docs for generated properties in PropertyMapper" am: 46a915f6

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/2165102



Change-Id: Ie0900ec085aa552075dc2f147125e0035d02b098
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>