public void testIsEqualToNull_apply() {
    Predicate<@Nullable Integer> isNull = Predicates.equalTo(null);
    assertTrue(isNull.apply(null));
    assertFalse(isNull.apply(1));
  }

  public void testIsEqualToNull_equality() {
    new EqualsTester()
        .addEqualityGroup(
            Predicates.<@Nullable Integer>equalTo(null),
            Predicates.<@Nullable Integer>equalTo(null))