[automerger skipped] DO NOT MERGE Cherry-pick: ICU-20536 Japanese era Reiwa support in ICU4J 56 am: 18c03b9631 -s ours am: b0ffb16c65 -s ours am: 0787e23688 -s ours am: b67a881144 -s ours am: 1e7cf5bdda -s ours am: 91a1624233 -s ours
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Change-Id: I9bda426916e95390f6beb106ca5c3fff1e8b2982