Nginx offloading SSL and Tomcat to understand if the request was initally on HTTPS

Good day all,
i have an issue with NGINX correctly managin my tomcat as reverse proxy.

1 istance of Tomcat is managing an application that was originally direct connected to port 80/443.
Application to logon users understand if the request comes from HTTP or HTTPS and manage all the logon to be on HTTPS.

Now, with NGINX in front of it, all the requests come as HTTP, because i'm offloading SSL traffic directly to NGINX.
It is working like a charm, but i'm not more able to understand it it was originally coming from HTTP or HTTPS.

How i can deal with it?

Some header to add to nginx maybe?

Thank you in advance.

Regards,