* has read the inital source data into a Row object. Typically, this would be
* used to add data to the row, manipulate the data into a canonical form, or
* signal by exception that the row should be skipped. The event listener
* has read the inital source data into a Row object. Typically, this would be
* used to add data to the row, manipulate the data into a canonical form, or
* signal by exception that the row should be skipped. The event listener