private ResourceBundle getBundle(String name) {
        String bundleKey = getBundleKey(name);
        if (bundles.containsKey(bundleKey)) {
            return bundles.get(bundleKey);
        } else {
            ResourceBundle bundle = loadBundle();
            bundles.put(bundleKey, bundle);
            return bundle;
        }
    }
Gets a bundle.  First tries to find one in the cache, then loads it if
it can't find one.
common/util/src/main/java/io/apiman/common/util/AbstractMessages.java