code: public synchronized void setDeviceName(String name) {
          if (name.getBytes().length > DEVICE_NAME_LENGTH) {
              throw new IllegalArgumentException("name cannot be more than " + DEVICE_NAME_LENGTH + " bytes long");
          }
          Arrays.fill(announcementBytes, DEVICE_NAME_OFFSET, DEVICE_NAME_LENGTH, (byte)0);
          System.arraycopy(name.getBytes(), 0, announcementBytes, DEVICE_NAME_OFFSET, name.getBytes().length);
      }
docs: Set the name to be used in announcing our presence on the network. The name can be no longer than twenty
  bytes, and should be normal ASCII, no Unicode.
  
  @param name the device name to report in our presence announcement packets.