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

am: 5f236d9a

* commit '5f236d9a':
  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: I33b547bb9fe12459558033e6264f3795ec42cee7