code: String
  rrToString() {
  	StringBuffer sb = new StringBuffer();
  	sb.append(certificateUsage);
  	sb.append(" ");
  	sb.append(selector);
  	sb.append(" ");
  	sb.append(matchingType);
  	sb.append(" ");
  	sb.append(base16.toString(certificateAssociationData));
  
  	return sb.toString();
  }
docs: Converts rdata to a String