public Object mapRow(ResultSet rs, int rowNum) throws SQLException {
// Validate column count.
ResultSetMetaData rsmd = rs.getMetaData();
int nrOfColumns = rsmd.getColumnCount();
if (nrOfColumns != 1) {
throw new IncorrectResultSetColumnCountException(1, nrOfColumns);
}
// Extract column value from JDBC ResultSet.
Object result = getColumnValue(rs, 1, this.requiredType);
if (result != null && this.requiredType != null && !this.requiredType.isInstance(result)) {