Header propagation with Flurl and DotNetCore

I've really enjoyed using Flurl the last year but have encountered a problem that Im hoping I can solve using Flurl if possible and not resort ripping it out and using IHttpClientFactory and HttpClient from System.Net.Http

I've got a DotNetCore 3.1 API and our client is calling these APIs with custom headers. "x-activityid" as an example. My API calls out to an external API and so I've created a separate Client class where im calling the endpoints on the external API using Flurl.

I need to propagate some of the headers from the requests incomming to my API to the requests I make to the external API that Im calling using Flurl.

Some related links:

• Header propagation using ASP.NET Core
• Make HTTP requests using IHttpClientFactory in ASP.NET Core