Iterator<String> filtered = Iterators.filter(unfiltered, Predicates.alwaysFalse());
    List<String> expected = Collections.emptyList();
    List<String> actual = Lists.newArrayList(filtered);
    assertEquals(expected, actual);
  }

  public void testFilterMatchAll() {
    Iterator<String> unfiltered = Lists.newArrayList("foo", "bar").iterator();
    Iterator<String> filtered = Iterators.filter(unfiltered, Predicates.alwaysTrue());

                    Version.V20,
                    "modelVersion",
                    null,
                    "of '" + string + "' is older than the versions supported by this version of Maven: "
                            + validVersions + ". Building this project requires an older version of Maven.",
                    tracker);

        } else {
            addViolation(
                    problems,