Polish "Support @Order on [CommandLine|Application]Runner @Bean definitions"

See gh-37905

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/ApplicationRunner.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/CommandLineRunner.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/SpringApplicationTests.java

@@ -670,11 +670,11 @@ class SpringApplicationTests {
 	}
 
 	@Test
-	void runFunctionalCommandLineRunnersAndApplicationRunners() {
-		SpringApplication application = new SpringApplication(FunctionalRunnerConfig.class);
+	void runCommandLineRunnersAndApplicationRunnersUsingOrderOnBeanDefinitions() {
+		SpringApplication application = new SpringApplication(BeanDefinitionOrderRunnerConfig.class);
 		application.setWebApplicationType(WebApplicationType.NONE);
 		this.context = application.run("arg");
-		FunctionalRunnerConfig config = this.context.getBean(FunctionalRunnerConfig.class);
+		BeanDefinitionOrderRunnerConfig config = this.context.getBean(BeanDefinitionOrderRunnerConfig.class);
 		assertThat(config.runners).containsExactly("runnerA", "runnerB", "runnerC");
 	}
 
@@ -1585,12 +1585,12 @@ class SpringApplicationTests {
 	}
 
 	@Configuration(proxyBeanMethods = false)
-	static class FunctionalRunnerConfig {
+	static class BeanDefinitionOrderRunnerConfig {
 
-		List<String> runners = new ArrayList<>();
+		private final List<String> runners = new ArrayList<>();
 
 		@Bean
-		@Order // default is LOWEST_PRECEDENCE
+		@Order
 		CommandLineRunner runnerC() {
 			return (args) -> this.runners.add("runnerC");
 		}