docs: private static void addFields(CtClass clazz) throws CannotCompileException, NotFoundException {
          CtField tail = CtField.make(String.format("private Map %s = new HashMap();", TAIL_FIELD), clazz);
          clazz.addField(tail);
          String loggerDefinition = "private static final Logger %s = LoggerFactory.getLogger(%s.class.getName());";
          CtField logger = CtField.make(String.format(loggerDefinition, LOGGER_FIELD, clazz.getName()), clazz);
          clazz.addField(logger);
      }