Merge changes from topic \'icu_cp_catchup\' am: f6aabd95 am: 2b44297f am: 5f236d9a

am: 87afd022

* commit '87afd022':
  Track external/icu API changes for factory registration
  ICU4J: Hide constants that can change between releases
  Remove RawCollationKey/ByteArrayWrapper from the public API

Change-Id: I54d92e371bc26a470730c495ab2d070cecf0f266