java:S6204 Suggestion of using .toList() in a List that is from the interface does not compile

[Irineu_Ruiz]

SonarCloud is constantly asked to use .toList() in addition to .collect(Collectors.toList()) but in some cases this request is wrong as the solution simply won’t compile.

Here’s a small example:

@RequiredArgsConstructor
public class ReturnTestSonar {
    @Getter private final List<TestSonar> list;
    
    @RequiredArgsConstructor
    public static class TestSonarImpl implements TestSonar {
        @Getter private final Integer integer;
    }

}


public class SonarViolation {
        
    public List<TestSonar> teste(List<Integer> list) {
        return list.stream().map(TestSonarImpl::new).collect(Collectors.toList());
    }
    
    public ReturnTestSonar myList(List<Integer> list) {
        return new ReturnTestSonar(list.stream().map(TestSonarImpl::new).collect(Collectors.toList())); 
    }
}

The solution not compile, because then I would have to change the return of the method to be the TestSonarImpl instead of the interface TestSonar.

[irina.batinic]

Hi @Irineu_Ruiz,

I tried reproducing this issue, but without success.
Can you please check if you added an intended code example?
Also, does the rule raise in SonarLint?
Thanks!

All the best,

Irina

[Irineu_Ruiz]

Hi @irina.batinic ,

We use Sonarlint and Sonar cloud with the default settings.
Apparently the problem has already been resolved, I tested it today and now it is no longer giving the java:S6204 violation.
Even our production code that reported this has now stopped reporting in Sonar Cloud.

Thank you very much, it’s resolved.