I have been through the current code to implement this change:

01- it is all easy upto when I got to the implementation of PartListConsumer and FixedConsumer, when handling the buffers' capacity, marks and limits

02- when integrating with other tools such as Apache Wicket or other servlet based API, it then shows up that the proper javax.servlet.ServletRequest#getContentLength() method has return type of int, not long thus being there the size limit origin

I will need more time to understand the chosen strategies for handling of buffers.