it is needed for the derived datasource to add to its properties some descriptive information that is found in a property whose value is a Controller service.
By providing the keys to the datasource-defintion.json this can now be done.
1. Add to the "datasourcePropertyKeys" the extra keys needed that will look at the controller service using this notation:
Example for the GetTableData processor:
Example in its entirety:
This will then add the value of that property into the derived datasource when the feed is saved.