File Provider not prefilling target

Problem/Motivation

When using the file provider (e.g. xliff), I can choose wether the target is empty or "same as source". How can I configure the plugin so that the target gets prefilled with an existing translation?

Steps to reproduce

Translate a taxonomy term to e.g. german.
Under sources add this term to the cart.
From the cart create a job with the file provider.
The exported xliff file contains either no target or is prefilled with the source text.

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes