Changes in validation on /orders and /invoices
We would like to notify about upcoming changes for the REST API, where we are planning to introduce stronger validation rules on certain endpoints in order to provide better feedback to the users/developers early in the creation process.

One of such places is line numbers on /orders and /invoices, where the current implementation lacks transparency. The coming implementation will provide a validation error in case duplicate line numbers are present on write operations. In case line numbers are not defined in the request, we will assign them incrementally. Furthermore, sortKeys will be assigned index-based. So the way you sort them in the request is how they’ll end up sorted in the application and PDFs.

The changes will be effective from 24.07.2018.