val b1 = source.readByte() and 0xff

    val isMasked = b1 and B1_FLAG_MASK != 0
    if (isMasked == isClient) {
      // Masked payloads must be read on the server. Unmasked payloads must be read on the client.
      throw ProtocolException(
        if (isClient) {
          "Server-sent frames must not be masked."
        } else {
          "Client-sent frames must be masked."

   ([#122724](https://github.com/kubernetes/kubernetes/pull/122724), [@nayihz](https://github.com/nayihz))
- In the Pod API, setting the alpha `procMount` field to `Unmasked` in a container now required setting `spec.hostUsers=false` as well.
   ([#123520](https://github.com/kubernetes/kubernetes/pull/123520), [@haircommander](https://github.com/haircommander))