ChatGPT4 writes Stan code so I don’t have to(statmodeling.stat.columbia.edu)

  public class DiameterHeader {
    private int version;
    private long messageLength;
    private int commandFlags;
    private long commandCode;
    private long applicationId;
    private long hopByHopId;
    private long endToEndId;

    public DiameterHeader(byte[] data) {
        if (data == null || data.length != 20) {
            throw new IllegalArgumentException("Invalid Diameter header data");
        }

        version = data[0] & 0xFF;
        messageLength = ((long) data[1] & 0xFF) << 16 | ((long) data[2] & 0xFF) << 8 | ((long) data[3] & 0xFF);
        commandFlags = data[4] & 0xFF;
        commandCode = ((long) data[5] & 0xFF) << 16 | ((long) data[6] & 0xFF) << 8 | ((long) data[7] & 0xFF);
        applicationId = (((long) data[8] & 0xFF) << 24) | (((long) data[9] & 0xFF) << 16) | (((long) data[10] & 0xFF) << 8) | ((long) data[11] & 0xFF);
        hopByHopId = (((long) data[12] & 0xFF) << 24) | (((long) data[13] & 0xFF) << 16) | (((long) data[14] & 0xFF) << 8) | ((long) data[15] & 0xFF);
        endToEndId = (((long) data[16] & 0xFF) << 24) | (((long) data[17] & 0xFF) << 16) | (((long) data[18] & 0xFF) << 8) | ((long) data[19] & 0xFF);
    }

    // Getters for the fields
  }