[java][doc] Fix Makdown examples: wrong collection type used to initialize Sets

[robinmarechal]

As mentioned in #23072 (comment), the generated documentation uses Arrays.asList() to initialize arrays, without checking uniqueItems Cf. AbstractJavaCodegen#setParameterExampleValue(CodegenParameter).

This leads to invalid examples like Set<String> tags = Arrays.asList();

This simple change checks uniqueItems. If true, it uses new LinkedHashSet<>() instead of Arrays.asList().

I did not create a new issue for this simple change, if I should create one just tell me.

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Summary by cubic

Fix Java docs example generation: when uniqueItems is true, Set examples now use LinkedHashSet instead of Arrays.asList. This prevents invalid examples like Set tags = Arrays.asList() and updates the petstore sample docs accordingly.

^{Written for commit 7955375. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 30 files

[Chrimle]

Why use a concrete implementation? Cleaner, and less opinionated to use the more common Set static methods.

[Chrimle]

Suggested change

	example = "new LinkedHashSet<>()";
	example = "Set.of()";

[Chrimle]

This comment is not relevant, and may be marked as "resolved" 👍

[Chrimle]

Suggested change

	example = "new LinkedHashSet<>(" + example + ")";
	example = "Set.of(" + example + ")";

[robinmarechal]

afaik, Set.of(Arrays.asList(xxx)) will create a Set<List<Xxx>>, not a Set<Xxx>.
So this change would generate an invalid syntax.

Also, the reason for the LinkedHashSet instead of Set is to keep insertion order. But yeah, in those examples the element order doesn't really matter.

I can use Set.of() for the empty set, but not here

[Chrimle]

Hmm, ordering in Sets is an interesting topic. I'm not sure if there is an established standard set in either OpenAPI or openapi-generator 🤔 (I just realized that LinkedHashSet is THE standard used in openapi-generator, so this is a non-issue)

Yeah, I did not know what the type of example was, that would indeed be incorrect 😄

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I left my comment a bit open-ended, because I wasn't completely sure, but now I'm convinced this is the correct solution 👍 Thanks for the patience @robinmarechal 😊

[Chrimle]

How come I cannot resolve my own comments @wing328, is that an admin feature? 🤔

[wing328]

i've no idea either.

[Chrimle]

Looks great ❤️