Improvement: Make GrailsApplicationPostProcessor implements Ordered

[rainboyan]

Feature description

Spring Framework invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered first, then Ordered, and the rest will be last invoked.

But GrailsApplicationPostProcessor is not Ordered, If Grails user create a BeanDefinitionRegistryPostProcessor and configure in Application, GrailsApplicationPostProcessor will be invoked after DemoBeanDefinitionRegistryPostProcessor, it is not as we expected.

Application,

class Application extends GrailsAutoConfiguration {
    static void main(String[] args) {
        GrailsApp.run(Application, args)
    }

    @Bean
    DemoBeanDefinitionRegistryPostProcessor demoBeanDefinitionRegistryPostProcessor() {
        new DemoBeanDefinitionRegistryPostProcessor()
    }
}

DemoBeanDefinitionRegistryPostProcessor,

class DemoBeanDefinitionRegistryPostProcessor implements BeanDefinitionRegistryPostProcessor, Ordered {
    @Override
    void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
        log.info("postProcessBeanDefinitionRegistry")
    }

    @Override
    void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        log.info("postProcessBeanFactory")
        BeanFactory parentBeanFactory = beanFactory.getParentBeanFactory()
        if (parentBeanFactory instanceof ConfigurableBeanFactory) {
            ConfigurableBeanFactory configurableBeanFactory = parentBeanFactory
            log.info("GrailsPluginManager exists? " + configurableBeanFactory.containsSingleton(GrailsPluginManager.BEAN_NAME))
        }
    }

    @Override
    int getOrder() {
        return 0
    }
}

When grails run-app, The log will look like this:

2022-05-30 17:31:48.520  INFO --- [  restartedMain] .DemoBeanDefinitionRegistryPostProcessor : postProcessBeanFactory
2022-05-30 17:31:48.523  INFO --- [  restartedMain] .DemoBeanDefinitionRegistryPostProcessor : GrailsPluginManager exists? false

The demo code here: https://github.com/rainboyan/grails-application-post-processor-ordered-issue