RFR: 8346659: SnippetTaglet should report an error if provided ambiguous links

Tue Jan 28 11:34:44 UTC 2025

Some javadoc snippets can match multiple links to the same content, leading to different results in different javadoc runs.
This patch proposes emitting an error when such cases are encountered.

There is a very trivial, unrelated change in `TestGlobalHtml.java` because I noticed some whitespace wasn't right.

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Commit messages:
 - emit error when encountering ambigious link

Changes: https://git.openjdk.org/jdk/pull/23328/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23328&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8346659
  Stats: 111 lines in 4 files changed: 82 ins; 12 del; 17 mod
  Patch: https://git.openjdk.org/jdk/pull/23328.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23328/head:pull/23328

PR: https://git.openjdk.org/jdk/pull/23328