ODATA Integration - Header?

Hi all,

I am trying to access an OData REST API that I manage using SAP BTP API Management.
So far, so good: it is working using the “REST API direct integration”.
However, it would make sense to use that REST API over “OData Integration” since it features a couple of more possibilities on the UI, thanks to the metadata.
The issue: my REST API requires an API key (that’s a simple best practice). This “apikey” is sent over a header.
Question: how do I send headers to the REST API when using “OData Integration” as data source?