docs: static byte[] mask(byte[] maskingKey, byte[] payload)
      {
          if (maskingKey == null || maskingKey.length < 4 || payload == null)
          {
              return payload;
          }
  
          for (int i = 0; i < payload.length; ++i)
          {
              payload[i] ^= maskingKey[i % 4];
          }
  
          return payload;
      }