static void validateFallbackFactory(final Class clazz) {
        Assert.isTrue(!clazz.isInterface(), "Fallback factory must produce instances " + "of fallback classes that implement the interface annotated by @ShenyuClient");
    }
Validate fallback factory.
@param clazz the clazz
shenyu-sdk/shenyu-sdk-feign/src/main/java/org/apache/shenyu/sdk/feign/ShenyuClientsRegistrar.java