[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: 3f055f5bde -s ours
am: f6644e9bc0 -s ours
am skip reason: subject contains skip directive

Change-Id: Ia6514e20b707eea418e0eb0b890eacbbf94ba252