RFR: JDK-8295071: Spec Clarification : ClassFileFormatVersion: System property java.class.version | Java class format version number

[Joe Darcy]

Document existing behavior.

Please also review the CSR https://bugs.openjdk.org/browse/JDK-8309415

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Commit messages:
 - JDK-8309415: Spec Clarification : ClassFileFormatVersion: System property java.class.version | Java class format version number

Changes: https://git.openjdk.org/jdk/pull/14305/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14305&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8295071
  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/14305.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14305/head:pull/14305

PR: https://git.openjdk.org/jdk/pull/14305