[automerger skipped] DO NOT MERGE Cherry-pick: ICU-20536 Japanese era Reiwa support in ICU4J 60 am: a83e435ffa -s ours
am: 2ed87f390d -s ours
am skip reason: subject contains skip directive

Change-Id: Iefc9d1d44758e4bbf5b9ea0ba7b481b69f11dd38