Introduce SetStream Refaster rule

[mohamedsamehsalah]

I think this is a candidate for "combinations of operators that don't make sense".

I tried to extend the rule with rules like

  static final class SetStreamFilter<T> {
    @BeforeTemplate
    Stream<?> before(Set<T> set, Predicate<T> predicate) {
      return set.stream().filter(predicate).distinct();
    }

    @AfterTemplate
    Stream<?> after(Set<T> set, Predicate<T> predicate) {
      return set.stream().filter(predicate);
    }
  }

But the number of permutations of different operators before using #distinct is a lot.

Suggested commit message

Rely on Set's property to preserve distinct elements when streaming

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[Stephan202]

Added a commit.

Suggested commit message:

Introduce `SetStream` Refaster rule (#1264)

[Stephan202]

This does assume that the set doesn't use a custom equality, like a SortedSet might. Will add a note:

Suggested change

	/** Rely on Set's property to preserve distinct elements. */
	/** Don't unnecessarily call {@link Stream#distinct()} on an already-unique stream of elements. */
	// XXX: This rule assumes that the `Set` relies on `Object#equals`, rather than a custom
	// equivalence relation.
	// XXX: Expressions that drop or reorder elements from the stream, such as `.filter`, `.skip` and
	// `sorted`, can similarly be simplified. Covering all cases is better done using an Error Prone
	// check.

(I'm not too worried about false positives: it's likely rare that there is code that wants cares about both types of deduplication in a single context.)

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[mohamedsamehsalah]

🧠

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[rickie]

@hpnog Any additions from your side :)?

[mohamedsamehsalah]

@hpnog Any additions from your side :)?

Discussed offline: We can proceed without @hpnog 's input.

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud