StreamReceiver for receiving incoming data stream

To receive upload from the client we need to register a StreamReceiver that will get a URL that will handle receiving of an upload stream.

For creating a StreamReceiver we first need to create a StreamVariable that handles terminal Upload monitors and controls the upload during the time it is being streamed.

Then the stream can be registered through the Element API.

StreamReceiver streamReceiver = new StreamReceiver(
    getElement().getNode(), "upload", getStreamVariable());
getElement().setAttribute("target", streamReceiver);