public static @NotNull DomInvocationHandler getNotNullHandler(DomElement proxy) {
    DomInvocationHandler handler = getDomInvocationHandler(proxy);
    if (handler == null) {
      throw new AssertionError("null handler for " + proxy);
    }
    return handler;
  }
public static @NotNull DomInvocationHandler getNotNullHandler(DomElement proxy)