I've added a method to the FormatFields implementation with a provided default implementation based on what was already in the add_fields method. This is potentially a breaking change in a subtle manner as anyone who has manually implemented the add_fields method will most likely also want to implement this.
When fields should be printed, they are first printed to a new instance and then they are merged with the original.
Motivation
1565
Solution
I've added a method to the
FormatFieldsimplementation with a provided default implementation based on what was already in theadd_fieldsmethod. This is potentially a breaking change in a subtle manner as anyone who has manually implemented theadd_fieldsmethod will most likely also want to implement this.When fields should be printed, they are first printed to a new instance and then they are merged with the original.