RFR: 8267587: Update java.util to use enhanced switch [v6]

[Tagir F.Valeev]

> Inspired by PR#4088. Most of the changes are done automatically using IntelliJ IDEA refactoring. Some manual adjustments are also performed, including indentations, moving comments, extracting common cast out of switch expression branches, etc.
> 
> I also noticed that there are some switches having one branch only in JapaneseImperialCalendar.java. Probably it would be better to replace them with `if` statement?

Tagir F. Valeev has updated the pull request incrementally with two additional commits since the last revision:

 - JapaneseImperialCalendar: use switch expressions
 - Use yield in java.util.Calendar.Builder.build

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4161/files
  - new: https://git.openjdk.java.net/jdk/pull/4161/files/f4ad5f14..e8cdf10e

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4161&range=05
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4161&range=04-05

  Stats: 155 lines in 2 files changed: 56 ins; 61 del; 38 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4161.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4161/head:pull/4161

PR: https://git.openjdk.java.net/jdk/pull/4161