[automerger skipped] DO NOT MERGE Cherry-pick: ICU-20536 Japanese era Reiwa support in ICU4J 58 am: fc5a01ba3d -s ours
am: 8eb668d374 -s ours
am skip reason: subject contains skip directive

Change-Id: Ic348fbccf969786a99e632a738d10ef5bbe83c09