Reduce csv feeder to a subset of records before applying flattenMapIntoAttributes

For the following code, I would like to change searchRecords by applying conditional logic so that if the value of a column in the csv matches a specific value, I include it. The idea is to be able to get different subsets of records for different cases. How would I do something like that? And would it possible to trigger that based on a value entered as a system property on the maven commandline?