public static PackageTally combine(Collection<PackageTally> packageTallies) {
        var definedPkgs = new HashMap<String, PackageInfo>();
        Set<String> referencedPkgs = new HashSet<>();

        for (PackageTally tally : packageTallies) {
            tally.definedPackages.forEach((pkg, info) -> definedPkgs.merge(pkg, info, PackageInfo::hasExportPackageOrElse));
            referencedPkgs.addAll(tally.referencedPackagesUnfiltered);
        }
        return new PackageTally(definedPkgs, referencedPkgs);
    }
Represents the classes for two package tallies that are deployed as a single unit.
<p>
ExportPackageAnnotations from this has precedence over the other.
TODO: Add unit test and try using Map.merge (as in the functions below). Can't see how Maps.combine is any different.
bundle-plugin/src/main/java/com/yahoo/container/plugin/classanalysis/PackageTally.java