code: @NotNull
      public static OptionalDouble ofNullable(@Nullable Double value) {
          return value == null ? EMPTY : new OptionalDouble(value);
      }
docs: Returns an {@code OptionalDouble} with the specified value, or empty {@code OptionalDouble} if value is null.
  
  @param value the value which can be null
  @return an {@code OptionalDouble}
  @since 1.2.1