docs: public QRSCT text(String text) {
  		if (text != null && text.length() <= 140) {
  			this.reference = ""; //$NON-NLS-1$
  			this.text = checkValidSigns(text);
  			return this;
  		}
  		throw new IllegalArgumentException("supplied text [" + text //$NON-NLS-1$
  				+ "] not valid: has to be not null and of max length 140"); //$NON-NLS-1$
  	}