RFR: JDK-8310909: java.io.InvalidObjectException has redundant `@since` tag

[Jonathan Gibbons]

Please review a trivial update to remove a redundant `@since` tag.

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Commit messages:
 - JDK-8310909: java.io.InvalidObjectException has redundant `@since` tag

Changes: https://git.openjdk.org/jdk/pull/14662/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14662&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310909
  Stats: 2 lines in 1 file changed: 0 ins; 2 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/14662.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14662/head:pull/14662

PR: https://git.openjdk.org/jdk/pull/14662