@Override
  public String toString() {
    return MoreObjects.toStringHelper(this)
        .add("key", mName)
        .add("values", formatValues(mValues))
        .toString();
  }
@Test
  public void testToString() {
    InconsistentProperty inconsistentProperty = createInconsistentProperty();
    String result = inconsistentProperty.toString();
    Assert.assertFalse(result.contains("Optional"));
    String expected = "InconsistentProperty{key=my_key, values="
        + "no value set (workerHostname1:workerPort, workerHostname2:workerPort), "
        + "some_value (masterHostname1:port, masterHostname2:port)}";
    Assert.assertEquals(expected, result);
  }