private static boolean isFragment(Bundle bundle) {
        BundleRevision bundleRevision = bundle.adapt(BundleRevision.class);
        if (bundleRevision == null)
            throw new NullPointerException("Null bundle revision means that bundle has probably been uninstalled: " +
                                                   bundle.getSymbolicName() + ":" + bundle.getVersion());
        return (bundleRevision.getTypes() & BundleRevision.TYPE_FRAGMENT) != 0;
    }
Resolves and starts (calls the Bundles BundleActivator) all bundles. Bundle resolution must take place
after all bundles are installed to ensure that the framework can resolve dependencies between bundles.
container-core/src/main/java/com/yahoo/container/core/config/BundleStarter.java