RFR: JDK-8304991: Redundant hyphen in @param results in double-dash in javadocs

[Harshitha Onkar]

Minor change to Javadoc. Removed redundant hyphen for @param.

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Commit messages:
 - removed extra hyphen

Changes: https://git.openjdk.org/jdk/pull/13218/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13218&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8304991
  Stats: 5 lines in 4 files changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/13218.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13218/head:pull/13218

PR: https://git.openjdk.org/jdk/pull/13218