code: @Override
      public Stream<P_OUT> unordered() {
          if (!isOrdered())
              return this;
          return new StatelessOp<P_OUT, P_OUT>(this, StreamShape.REFERENCE, StreamOpFlag.NOT_ORDERED) {
              @Override
              public Sink<P_OUT> opWrapSink(int flags, Sink<P_OUT> sink) {
                  return sink;
              }
          };
      }
docs: Stateless intermediate operations from Stream