RFR: 8253455: Record Classes (final) javax.lang.model changes [v3]

[Vicente Romero]

> Please review the fix for [JDK-8253455](https://bugs.openjdk.java.net/browse/JDK-8253455) which is part of the effort
> to make records a final feature of the Java Language. The rest of the code has been published in
> [PR#290](https://github.com/openjdk/jdk/pull/290)  Thanks,
> Vicente

Vicente Romero has refreshed the contents of this pull request, and previous commits have been removed. The incremental
views will show differences compared to the previous content of the PR. The pull request contains one new commit since
the last revision:

  adding reminder to remove RECORDS from PreviewFeature

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/291/files
  - new: https://git.openjdk.java.net/jdk/pull/291/files/9b24af7d..f0845f6f

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=291&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=291&range=01-02

  Stats: 0 lines in 0 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/291.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/291/head:pull/291

PR: https://git.openjdk.java.net/jdk/pull/291