public static DoubleStream stream(OptionalDouble optional) {
    return optional.isPresent() ? DoubleStream.of(optional.getAsDouble()) : DoubleStream.empty();
  }

  @SuppressWarnings("CatchingUnchecked") // sneaky checked exception
  private static void closeAll(BaseStream<?, ?>[] toClose) {
    // If one of the streams throws an exception, continue closing the others, then throw the

   * An implementation of {@link ExecutorService#invokeAny} for {@link ListeningExecutorService}
   * implementations.
   */
  @SuppressWarnings({
    "GoodTime", // should accept a java.time.Duration
    "CatchingUnchecked", // sneaky checked exception
    "Interruption", // We copy AbstractExecutorService.invokeAny. Maybe we shouldn't: b/227335009.
  })
  @J2ktIncompatible
  @GwtIncompatible
  @ParametricNullness