public void testOr_optional_present() {
    assertEquals(Optional.of("a"), Optional.of("a").or(Optional.of("fallback")));
  }

  public void testOr_optional_absent() {
    assertEquals(Optional.of("fallback"), Optional.absent().or(Optional.of("fallback")));
  }

  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
  public void testOrNull_present() {