RFR: 8313239: InetAddress.getCanonicalHostName may return ip address if reverse lookup fails [v6]

[Jaikiran Pai]

> Can I please get a review of this change which updates the javadoc of `java.net.InetAddress.getCanonicalHostName()` method to clarify its semantics? This addresses https://bugs.openjdk.org/browse/JDK-8313239.
> 
> This a javadoc only change and the documentation is updated to match the current implementation. A CSR will be drafted for this change.

Jaikiran Pai has updated the pull request incrementally with one additional commit since the last revision:

  Aleksei's review

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Changes:
  - all: https://git.openjdk.org/jdk/pull/15134/files
  - new: https://git.openjdk.org/jdk/pull/15134/files/9ff86180..c9c3ba8b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15134&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15134&range=04-05

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/15134.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15134/head:pull/15134

PR: https://git.openjdk.org/jdk/pull/15134