Merge changes from topic \'icu_cp_catchup\'
am: f6aabd95df

* commit 'f6aabd95df71e5b64a0b3806a7632954ed7cfd99':
  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: Ifd6e4730450211a586ac8a6abec71c1faa055e8c