RFR: 8307295: Add warning to not create new ACC flags [v2]

[Coleen Phillimore]

> Please comment on or review this new comment.  Thanks.

Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:

  Update with suggestion from John.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13757/files
  - new: https://git.openjdk.org/jdk/pull/13757/files/4139e7d2..dee204b8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13757&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13757&range=00-01

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13757.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13757/head:pull/13757

PR: https://git.openjdk.org/jdk/pull/13757