private Map<FileReference, Bundle> installBundles(List<FileReference> references) {
        Set<FileReference> bundlesToInstall = new HashSet<>(references);

        // This is just an optimization, as installing a bundle with the same location id returns the already installed bundle.
        bundlesToInstall.removeAll(activeBundles.keySet());

        if (bundlesToInstall.isEmpty()) return Map.of();

        if (bundleInstaller.hasFileDistribution()) {
            return installWithFileDistribution(bundlesToInstall, bundleInstaller);
        } else {
            log.warning("Can't retrieve bundles since file distribution is disabled.");
            return Map.of();
        }
    }
Returns the set of new bundles that were installed.
container-core/src/main/java/com/yahoo/container/core/config/ApplicationBundleLoader.java