tester.testEquals();
    } catch (AssertionFailedError e) {
      assertErrorMessage(e, "bar [group 1, item 2] must be Object#equals to foo [group 1, item 1]");
      return;
    }
    fail("should failed because symmetry is broken");
  }

  public void testTransitivityBrokenInEqualityGroup() {
    EqualsTester tester =
        new EqualsTester()
            .addEqualityGroup(

      tester.testEquals();
    } catch (AssertionFailedError e) {
      assertErrorMessage(e, "bar [group 1, item 2] must be Object#equals to foo [group 1, item 1]");
      return;
    }
    fail("should failed because symmetry is broken");
  }

  public void testTransitivityBrokenInEqualityGroup() {
    EqualsTester tester =
        new EqualsTester()
            .addEqualityGroup(

   * {@link TypeVariableImpl#equals(Object)} is changed to no longer be equal to custom TypeVariable
   * implementations. As a result, we need to make sure our TypeVariable implementation respects
   * symmetry. Moreover, we don't want to reconstruct a native type variable {@code <A>} using our
   * implementation unless some of its bounds have changed in resolution. This avoids creating

   * {@linkplain #intersection intersection} (as a single, possibly-empty range) if and only if this
   * method returns {@code true}.
   *
   * <p>The connectedness relation is both reflexive and symmetric, but does not form an {@linkplain
   * Equivalence equivalence relation} as it is not transitive.
   *
   * <p>Note that certain discrete ranges are not considered connected, even though there are no

   * {@linkplain #intersection intersection} (as a single, possibly-empty range) if and only if this
   * method returns {@code true}.
   *
   * <p>The connectedness relation is both reflexive and symmetric, but does not form an {@linkplain
   * Equivalence equivalence relation} as it is not transitive.
   *
   * <p>Note that certain discrete ranges are not considered connected, even though there are no

      public boolean contains(@CheckForNull Object element) {
        return set1.contains(element) && !set2.contains(element);
      }
    };
  }

  /**
   * Returns an unmodifiable <b>view</b> of the symmetric difference of two sets. The returned set
   * contains all elements that are contained in either {@code set1} or {@code set2} but not in
   * both. The iteration order of the returned set is undefined.
   *