When I am developing complex logic across multiple classes, I often log entities (often with toString() underneath) to check the status of the object, which field has what value. But I always find logs unnecessarily verbose, printing all fields. It is hard to track:

• what has been changed and
• when it is changed

when an entity goes a long way through a bunch of classes.

I would like to see only “tainted” fields(the fields which are already changed/set before reaching the logging line of code). I imagine a solution like this:

• set a value to a field
• add this field to a map, for example taintedFields; key is field name and value is actual value. Ideally, do this in every setter. Better yet, an abstract class with such setter template as base class for all model classes/DTOs, so that every setter would do super.tainted(field, value) before setting the value
• when printing, only print this map; other null/empty values are ignored

The idea is not hard to implement, but I wonder is this practical? Is it good practice? Is there any existing solution? I cannot be the first person ever to think about this. Any better way to do it?