R/Plumber: Rerouting Swagger UI through Nginx Reverse Proxy

Question

Background

I have a remote server on which an R API service is running by the use of Plumber. It is fully operational in the sense that I can call my service externally.

I am using an Ubuntu/Nginx reverse proxy setup. The Plumber service is listening to port 1163. I have subsequently implemented the following Nginx rerouting such that the API listens to https://server.net/API/:

location /API/ {
 proxy_pass http://localhost:1163/;
 proxy_redirect http://localhost:1163/ $scheme://$host/;
}

This is working fine. Now, by default, the Swagger UI listens to

http://127.0.0.1:1163/__swagger__/

which, owing to the config above, means that I can successfully access the Swagger UI at

https://server.net/API/__swagger__/

Issue

I want to configure Nginx such that the Swagger UI listens to https://server.net/API/documentation/. I have attempted the following nested Nginx configuration:

location /API/ {
 proxy_pass http://localhost:1163/;
 proxy_redirect http://localhost:1163/ $scheme://$host/;

 location /API/documentation/ {
 proxy_pass http://localhost:1163/__swagger__/;
 proxy_redirect http://localhost:1163/__swagger__/ $scheme://$host/;
 }

}

Now, while entering the desirable URL https://server.net/API/documentation/ into my browser, I retrieve the Swagger interface, however it returns the following error code:

Evidently, the incorrect swagger URL has been parsed during the Nginx redirection. This is clear considering that the url should state

https://server.net/API/swagger.json?schemes=https&host=server.net&path=/API/

instead of

http://petstore.swagger.io/v2/swagger.json

How can I ensure that the correct URL is parsed to the Swagger UI during the Nginx redirection? All the best, J.