Hi. StreamReaderProtocol was leaked implementation detail, not a public reusable class. The protocol has too many "gray zones" where its implementation is not well defined or even wrong. 

This situation prevents us from stream API improvements which require changing these implementation details. Keeping full backward compatibility literally means doubling source code, it makes no sense for "private" API but adds a huge maintenance burden.

We are striving to remove it from public API step by step: documentation-deprecation-removal.

If you really need the class -- please copy-paste the source lines into your project and use the copy on your own.