code: private void validateTableOptionShardingStart(TableDefinition tableDef, String optValue) {
          Utils.require(isValidShardDate(optValue),
                        "'sharding-start' must be YYYY-MM-DD: " + optValue);
          GregorianCalendar shardingStartDate = new GregorianCalendar(Utils.UTC_TIMEZONE);
          shardingStartDate.setTime(Utils.dateFromString(optValue));
  
          // 'sharding-start' requires 'sharding-field'
          Utils.require(tableDef.getOption(CommonDefs.OPT_SHARDING_FIELD) != null,
                        "Option 'sharding-start' requires option 'sharding-field'");
      }
docs: Validate the table option "sharding-start".