RFR: 8303214: Typo in java.util.Collections#synchronizedNavigableMap javadoc

[nbauma109]

I think this is a typo

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Commit messages:
 - Javadoc typo

Changes: https://git.openjdk.org/jdk/pull/11679/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11679&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303214
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/11679.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/11679/head:pull/11679

PR: https://git.openjdk.org/jdk/pull/11679