for (i in 0 until n) {
              sink.writeByte('x'.code)
            }
          } else {
            val buf = ByteArray(if (writeKind == WriteKind.SMALL_BUFFERS) 256 else 64 * 1024)
            Arrays.fill(buf, 'x'.code.toByte())
            var i = 0
            while (i < n) {
              sink.write(buf, 0, Math.min(buf.size, n - i))
              i += buf.size
            }