Hi Matthias, I have updated the KIP regarding points 103 and 108.
103. I have suggested a new `ImmutableHeaders` interface to deal with the immutability concern of the headers, which is basically the `Headers` interface without the write accesses. public interface ImmutableHeaders { Header lastHeader(String key); Iterable<Header> headers(String key); Header[] toArray(); } The `Headers` interface can be updated accordingly: public interface Headers extends ImmutableHeaders, Iterable<Header> { //… } Loïc