code: public Optional<String> getAssistedQueryColumn(final String logicTableName, final String columnName) {
          for (ShardingEncryptorStrategy each : shardingEncryptorStrategies.values()) {
              Optional<String> result = each.getAssistedQueryColumn(logicTableName, columnName);
              if (result.isPresent()) {
                  return result;
              }
          }
          return Optional.absent();
      }
docs: Get assisted query column.
  
  @param logicTableName logic table name
  @param columnName column name
  @return assisted query column