code: public static CronDefinition instanceDefinitionFor(final CronType cronType) {
          switch (cronType) {
              case CRON4J:
                  return cron4j();
              case QUARTZ:
                  return quartz();
              case UNIX:
                  return unixCrontab();
              case SPRING:
                  return spring();
              default:
                  throw new IllegalArgumentException(String.format("No cron definition found for %s", cronType));
          }
      }
docs: Creates CronDefinition instance matching cronType specification.
  
  @param cronType - some cron type. If null, a RuntimeException will be raised.
  @return CronDefinition instance if definition is found; a RuntimeException otherwise.