3. 执行BeanDefinitionRegistryPostProcessor(Ordered)

查找执行带 Ordered的BeanDefinitionRegistryPostProcessor
从注册的bean中查找实现带Ordered的BeanDefinitionRegistryPostProcessor，实例化并执行他们

postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
  if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
    currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
    processedBeans.add(ppName);
  }
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();