### Question:
ZuulBlockFallbackManager { public static synchronized void registerProvider(ZuulBlockFallbackProvider provider) { AssertUtil.notNull(provider, "fallback provider cannot be null"); String route = provider.getRoute(); if ("*".equals(route) || route == null) { defaultFallbackProvider = provider; } else { fallbackProviderCache.put(route, provider); } }  static synchronized void registerProvider(ZuulBlockFallbackProvider provider); static ZuulBlockFallbackProvider getFallbackProvider(String route); synchronized static void clear();  }### Answer:
@Test public void testRegisterProvider() throws Exception { MyNullResponseFallBackProvider myNullResponseFallBackProvider = new MyNullResponseFallBackProvider(); ZuulBlockFallbackManager.registerProvider(myNullResponseFallBackProvider); Assert.assertEquals(myNullResponseFallBackProvider.getRoute(), ROUTE); Assert.assertNull(myNullResponseFallBackProvider.fallbackResponse(ROUTE, new FlowException("flow ex"))); }