* expression {@code o -> Optional.toJavaUtil(o)} instead.
   *
   * @since 33.4.0 (but since 21.0 in the JRE flavor)
   */
  @SuppressWarnings({
    "AmbiguousMethodReference", // We chose the name despite knowing this risk.
    "NullableOptional", // Null passthrough is reasonable for type conversions
  })

   * expression {@code o -> Optional.toJavaUtil(o)} instead.
   *
   * @since 21.0 (but only since 33.4.0 in the Android flavor)
   */
  @SuppressWarnings({
    "AmbiguousMethodReference", // We chose the name despite knowing this risk.
    "NullableOptional", // Null passthrough is reasonable for type conversions
  })
  public static <T> java.util.@Nullable Optional<T> toJavaUtil(