RFR: JDK-8312418: Add Elements.getEnumConstantBody [v6]

[Joe Darcy]

> Trivial implementation to get feedback on the proposed API.

Joe Darcy has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 18 additional commits since the last revision:

 - Update copyright.
 - Merge branch 'master' into JDK-8312418
 - Refactor as suggested by jjg.
 - Reorder javadoc tags.
 - Change policy of default method.
 - Update printing processor.
 - Appease jcheck.
 - Merge in patch from Jan.
 - Merge branch 'master' into JDK-8312418
 - Merge branch 'master' into JDK-8312418
 - ... and 8 more: https://git.openjdk.org/jdk/compare/1ee5589c...0ac5b0cd

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/14939/files
  - new: https://git.openjdk.org/jdk/pull/14939/files/095eedb6..0ac5b0cd

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14939&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14939&range=04-05

  Stats: 21570 lines in 609 files changed: 15232 ins; 3321 del; 3017 mod
  Patch: https://git.openjdk.org/jdk/pull/14939.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14939/head:pull/14939

PR: https://git.openjdk.org/jdk/pull/14939