Merge "update CallControlCallback docs for the rejection case" into udc-dev am: e47056c3 am: 2408db82 am: e98b174d am: bce1d37e

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/22978378



Change-Id: Ife814604af06cf19365050c81eb3456664940aa7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>