[jdk21] RFR: 8310975: java.util.FormatItemModifier should not be protected

[Jim Laskey]

The nested class is incorrectly marked as protected.

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Commit messages:
 - Backport 315242b7417a4774765f139b841b385dc7c94c50

Changes: https://git.openjdk.org/jdk21/pull/72/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21&pr=72&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310975
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk21/pull/72.diff
  Fetch: git fetch https://git.openjdk.org/jdk21.git pull/72/head:pull/72

PR: https://git.openjdk.org/jdk21/pull/72