### Question:
DefaultResourceManager implements ResourceManager { public final void addResourceResolver(ResourceResolver resolver) { if (!registeredResolvers.contains(resolver)) { registeredResolvers.add(0, resolver); } } DefaultResourceManager();  DefaultResourceManager(ResourceResolver resolver);  DefaultResourceManager(List<? extends ResourceResolver> resolvers); final T resolveResource(String name, Class<T> type); final T resolveResource(String name, Class<T> type, List<ResourceResolver> resolvers); final InputStream getResourceAsStream(String name); final void addResourceResolver(ResourceResolver resolver); final void addResourceResolvers(Collection<? extends ResourceResolver> resolvers); final void removeResourceResolver(ResourceResolver resolver); final List<ResourceResolver> getResourceResolvers();  }### Answer:
@Test public void testAddDuplicateResolver() { manager.addResourceResolver(resolvers[1]); assertArrayEquals(resolvers, getResolvers(manager)); checkCallOrder(resolvers); }