RFR: 8280122: SupportedGroupsExtension should output "named groups" rather than "versions"

[John Jiang]

MessageFormat messageFormat = new MessageFormat(
    ""versions": '['{0}']'", Locale.ENGLISH);

In class SupportedGroupsExtension, the above "versions" should be "named groups".

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Commit messages:
 - 8280122: SupportedGroupsExtension should output "named groups" rather than "versions"

Changes: https://git.openjdk.java.net/jdk/pull/7123/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7123&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8280122
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7123.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7123/head:pull/7123

PR: https://git.openjdk.java.net/jdk/pull/7123