assertThrows(NullPointerException.class, () -> absentOptional.or(nullSupplier));
  }

  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
  public void testOr_nullSupplier_present() {
    Supplier<String> nullSupplier = (Supplier<String>) Suppliers.<@Nullable String>ofInstance(null);
    assertThat(Optional.of("a").or(nullSupplier)).isEqualTo("a");
  }