Fixing parsing of YAML tags in sequences

[Vishalup29]

fix(yaml): prevent duplicate tags in sequences

In some YAML sequences, tags were being rendered twice: once in the startBracketPrefix and once attached to the sequence. This caused idempotency issues when formatting YAML.

• Update YamlParser to only attach a tag if startBracketPrefix is null, resolving the failing test case in Idempotency issue with YAML tags used in sequences #5179.

What's changed?

A minor update to YamlParser to prevent duplicate tags in sequences. The parser now only attaches a tag to a sequence if startBracketPrefix is null, resolving the idempotency issue.

What's your motivation?

• Fixes a failing test case (Idempotency issue with YAML tags used in sequences #5179) where YAML sequences with tags were incorrectly rendered with the tag appearing twice: once in the prefix and once inside the brackets.

Anything in particular you'd like reviewers to focus on?

• The logic change at the SequenceStartEvent handling in YamlParser:

  if (sse.getTag() != null && startBracketPrefix == null) {
      ...
  }

Reviewers

@greg-at-moderne, @aet2505

[greg-at-moderne]

Please add a test - e.g. the one mentioned in the issue description.

[Vishalup29]

@greg-at-moderne Thanks for taking a look, I see the test was added by @timtebeek
Thanks for the test. Pls review/merge when possible

[greg-at-moderne]

Thanks for coming up with the PR.
I remember the @aet2505 had a comment about this feeling incorrect, but I fail to understand why.

[greg-at-moderne]

I suggest we merge it. I consider it an improvement. And if new information to light, we might find a better solution.

[aet2505]

My vague memory is that it felt like a bodge to me because it didn't parse the value as a 'Tag' correctly so potentially would have cases where if you tried to rewrite tags it might not behave as expected.

It definitely felt like it worked for me and I couldn't find the case where it failed!