filterUncachedPaths needs documentation

Problem/Motivation

I'm trying to debug issues with the --path-pattern Drush option, and I can't figure out what filterUncachedPaths() is doing.

    $this->eventDispatcher->dispatch($event, TomeStaticEvents::COLLECT_PATHS);
    $paths = $event->getPaths();
    dump($paths); // -- node paths are in this

    $paths = $this->cache->filterUncachedPaths($this->currentRequest->getSchemeAndHttpHost(), $paths);
    dump($paths); // node paths are now gone

What is the purpose for filtering? What are the criteria for filtering?

This code needs to explain why it is doing this.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes