remove hard coded attribute names if we allow integration with various systems

[rtarway]

https://github.com/rtarway/ecommerce-streamlytics-clickstream2/blob/fe843e52caccf28a2af8b91616e1353036ce32a7/src/main/java/com/beamlytics/inventory/businesslogic/core/transforms/stock/CountIncomingStockPerProductLocation.java#L55