@SuppressWarnings("unchecked") // safe covariant cast
  static <T extends @Nullable Object> Correspondence<T, T> equality() {
    return (Equality<T>) Equality.INSTANCE;
  }
@Test
  public void testEquality_viaIterableSubjectContains_success() {
    assertThat(ImmutableList.of(1.0, 2.0, 3.0)).comparingElementsUsing(equality()).contains(2.0);
  }