code: public int doRead(ByteChunk chunk) {
          if (!isNeedToRead()) {
              // Read only once.
              return -1;
          }
  
          read = true;
  
          final int readableBytes = content.length();
          chunk.setBytes(content.array(), content.offset(), readableBytes);
  
          return readableBytes;
      }
docs: Required for 8.5.