code: public void decode(int streamId, ByteBuf in, Http2Headers headers, boolean validateHeaders) throws Http2Exception {
          Http2HeadersSink sink = new Http2HeadersSink(streamId, headers, maxHeaderListSize, validateHeaders);
          decode(in, sink);
  
          // Now that we've read all of our headers we can perform the validation steps. We must
          // delay throwing until this point to prevent dynamic table corruption.
          sink.finish();
      }
docs: Decode the header block into header fields.
  <p>
  This method assumes the entire header block is contained in {@code in}.