docs: public String getColumnClassName(int column) throws SQLException
      {
          sourceResultSet.checkColumnBounds(column);
          VoltType type = sourceResultSet.table.getColumnType(column - 1);
          String result = type.getJdbcClass();
          if (result == null) {
              throw SQLError.get(SQLError.TRANSLATION_NOT_FOUND, type);
          }
          return result;
      }