code: protected void register(Class<? extends NlsBundle> bundleInterface, NlsBundle bundle) {
  
      NlsBundle old = this.bundleMap.put(bundleInterface, bundle);
      if (old != null) {
        throw new IllegalStateException("Duplicate bundle for " + bundleInterface);
      }
    }
docs: Registers the given {@code bundle} for the given {@code bundleInterface}.
  
  @param bundleInterface is the interface of the {@link NlsBundle}.
  @param bundle is the actual {@link NlsBundle} instance.