IntelliJ 13 Java 8 Compilation issue

Hi,

after starting IntelliJ 13 the following Java 8 code wouldn't compile anymore. Works without issues in v12 (and runs in Unit-Tests as well):

    public <T> Validator validate(T object, Class<?>... groups) {
        // ...
        Set<Violation> violations = constraintViolations.stream().map(this::convertToResult).collect(Collectors.toSet());
        // ...
    }

    private <T> Violation convertToResult(ConstraintViolation<T> violation) {
        // ...
        return new Violation();
    }

The Problem seems to be related to generic type detection on the violations assignment. It says the right-hand-side would return a Set<Object>, and nothing I tried would convince it otherwise.