// Length specified over multiple bytes.
          val lengthBytes = length0 and 0b0111_1111
          if (lengthBytes > 8) {
            throw ProtocolException("length encoded with more than 8 bytes is not supported")
          }

          var lengthBits = source.readByte().toLong() and 0xff
          if (lengthBits == 0L || lengthBytes == 1 && lengthBits and 0b1000_0000 == 0L) {