Generic typed objects cannot be used easily as optional parameters

[EotT123]

When trying to use generic typed objects (such as List<String>) as optional parameters, it is not possible to automatically infer the generic type. Instead, the type must be explicitly specified, otherwise, a type mismatch error occurs.

public class Test {

    //Incompatible types: 'List<Object>' cannot be converted to 'List<String>'
    public void test1(List<String> string = List.of()){ }

    //Incompatible types: 'ArrayList<Object>' cannot be converted to 'List<String>'
    public void test2(List<String> string = new ArrayList<>()){ }

    // OK
    public void test3(List<String> string = new ArrayList<String>()){ }
}

Is there a technical limitation that prevents generic types from being automatically inferred for optional parameters?

[rsmckinney]

Yep, this looks like an IntelliJ plugin issue. Default expression inference works fine with the compiler. Thanks for flagging this!