Fix issue 2943 - UnsolvedSymbolException thrown on Stream.<func>(<some lambda>)

[qzchenwl]

Fixes #2943.

[qzchenwl]

Lambda always has "function" type, never be void.

[MysterAitch]

I am confused about the sample used within this test:

import java.util.List;
import java.util.stream.IntStream;

public class Agenda {

    private List<String> persons;

    public void lambdaEmpty() {
        return persons.stream().forEach(p -> {
            System.out.println(p);
        });
    }

}

Note that .forEach() is void return type, AND lambdaEmpty is void return type... So why is there a return ...?

Which means that the original test is "wrong" or otherwise needs amending..?

[MysterAitch]

I add the above as a comment -- it doesn't change this PR 👍

Note this equivalent code where the parameter to stringConsumer is extracted as a variable with an explicit type:

    public void lambdaEmpty() {
        java.util.function.Consumer<String> stringConsumer = p -> {
            System.out.println(p);
        };
        persons.stream().forEach(stringConsumer);
    }