As an administrator I would like Confluence being less dependent on requests to itself

Problem Definition

There are some operations on which the Confluence backend server will need to make HTTP requests to its Base URL.
As an example, during PDF page export it will load some CSS files through HTTP requests to itself.

If there are additional security in the environment, such as enforced authentication through a Load Balancer, then those operations will be affected by it.
For the page PDF export example, if some CSS files are not properly loaded, then the PDF won't show the expected formatting.

A visual example of this problem, when using the Info, Warning or Note macros, the PDF export won't render them properly as the image below.
While the page looks normal from the browser:

The PDF export won't render it correctly:

Suggested Solution

Confluence should be less dependent on requests to its own Base URL, loading resources through the Java API.

Workaround

If enforcing authentication through a Load Balancer (or through a Marketplace App), then the administrator should configure a rule allowing unauthenticated requests from any Confluence node.