code: @Override
  	public void afterPropertiesSet() throws Exception {
  		super.afterPropertiesSet();
  		Assert.notNull(sql, "The SQL query must be provided");
  		Assert.notNull(rowMapper, "RowMapper must be provided");
  	}
docs: Assert that mandatory properties are set.
  
  @throws IllegalArgumentException if either data source or sql properties
  not set.