@Override
    public void startSelection(int numberOfLinks) {
        this.numberOfLinks = numberOfLinks;
        this.topkLinksPerDomain = new HashMap<>();
    }
Implements a link selection strategy that tries to select the top-k links from all different
top-level domains.
ache/src/main/java/achecrawler/link/frontier/selector/MaximizeWebsitesLinkSelector.java