RFR: JDK-8315458 Implement JEP 463: Implicitly Declared Classes and Instance Main Method (Second Preview) [v36]

[Jim Laskey]

> Address changes from JEP 445 to JEP 463.
> 
> - Move from a SYNTHETIC unnamed class to a MANDATED implicit class.
> 
> - Don't mark class on read.
> 
> - Remove reflection and annotation processing related to unnamed classes.
> 
> - Simplify main method search.

Jim Laskey has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 40 commits:

 - Merge remote-tracking branch 'upstream/master' into 8315458
 - Requested changes
 - Remove Test
 - Move findMainMethod to non-public access
 - Handle javadoc on top level elements properly
 - Update Class.java
 - Update test
 - Update findMainMethod as requested
 - Add nested class test
 - Move Implicitly Declared Classes to single directory
 - ... and 30 more: https://git.openjdk.org/jdk/compare/2fae07f5...daacc0ba

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Changes: https://git.openjdk.org/jdk/pull/16461/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16461&range=35
  Stats: 1294 lines in 51 files changed: 439 ins; 723 del; 132 mod
  Patch: https://git.openjdk.org/jdk/pull/16461.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16461/head:pull/16461

PR: https://git.openjdk.org/jdk/pull/16461