@Beta
  public static DoubleStream stream(OptionalDouble optional) {
    return optional.isPresent() ? DoubleStream.of(optional.getAsDouble()) : DoubleStream.empty();
  }
@Beta
  public static DoubleStream stream(OptionalDouble optional) {
    return optional.isPresent() ? DoubleStream.of(optional.getAsDouble()) : DoubleStream.empty();
  }
@ Beta public static DoubleStream stream ( OptionalDouble optional ) { return optional . isPresent ( ) ? DoubleStream . of ( optional . getAsDouble ( ) ) : DoubleStream . empty ( ) ; }
If a value is present in {@code optional}, returns a stream containing only that element,
otherwise returns an empty stream.

<p><b>Java 9 users:</b> use {@code optional.stream()} instead.
If a value is present in { @code optional } returns a stream containing only that element otherwise returns an empty stream .