Replace the placeholder Japanese era name

Summary

Replace the placeholder name for the Japanese new era with the government declared name.

Problem

The era name, "NewEra", was introduced with JDK-8202336 as the placeholder. However, the placeholder name does not represent "Reiwa".

Solution

Replace each instance of "NewEra" and its localized names made in JDK-8202336 and its square character (JDK-8211739) with the government declared name. Namely,

java.time.chrono.JapaneseEra:

The name of the JapaneseEra singleton that has the value of '3' will change from "NewEra" to "Reiwa". Thus,

• JapaneseEra.values() method will return 5 eras: [MEIJI, TAISHO, SHOWA, HEISEI, singleton representing "Reiwa"], the 5th item being changed from the one for "NewEra"
• JapaneseEra.of(3), JapaneseEra.valueOf("Reiwa"), and JapaneseChronology.eraOf(3) will return the singleton era that represents "Reiwa"
• JapaneseEra.getDisplayName() for the new era instance will return the localized display name of "Reiwa"
• JapaneseEra.valueOf("NewEra") will throw an IllegalArgumentException

java.util.Calendar:

The name of the era in JapaneseImperialCalendar that has the value of '5' will change from "NewEra" to "Reiwa". Thus,

new Calendar.Builder()
    .setCalendarType("japanese")
    .setFields(Calendar.ERA, 5,
        Calendar.YEAR, 1,
        Calendar.MONTH, Calendar.MAY,
        Calendar.DAY_OF_MONTH, 1)
    .build()
    .getDisplayName(Calendar.ERA, Calendar.LONG, Locale.US)

returns "Reiwa"

java.lang.Character:

The return value from Character.getName(0x32FF) will change from "SQUARE ERA NAME NEWERA" to "SQUARE ERA NAME REIWA".

Specification

This is behavioral change only and no spec change is expected. As to JapaneseEra changes, the era names are not part of their specifications, so changing the placeholder name to "Reiwa" does not warrant the specification changes.