Allow dependsOn relationships created by post-processor to be overridden

Previously, AbstractDependsOnBeanFactoryPostProcessor was unordered
which meant that it was impossible to guarantee that another bean
factory post-processor would run after it. This prevented overriding
of the dependsOn relationships that is creates.

This commit updates AbstractDependsOnBeanFactoryPostProcessor to give
it a default order of zero. This will allow additional bean factory
post-processors to be configured with a lower precedence order (values
greater than 0) so that they run after any
AbstractDependsOnBeanFactoryPostProcessor and can override the
dependencies that it has configured.

Fixes gh-18362

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/AbstractDependsOnBeanFactoryPostProcessor.java

@@ -30,6 +30,7 @@ import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.core.Ordered;
 import org.springframework.util.StringUtils;
 
 /**
@@ -45,7 +46,7 @@ import org.springframework.util.StringUtils;
  * @since 1.3.0
  * @see BeanDefinition#setDependsOn(String[])
  */
-public abstract class AbstractDependsOnBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
+public abstract class AbstractDependsOnBeanFactoryPostProcessor implements BeanFactoryPostProcessor, Ordered {
 
 	private final Class<?> beanClass;
 
@@ -114,6 +115,11 @@ public abstract class AbstractDependsOnBeanFactoryPostProcessor implements BeanF
 		}
 	}
 
+	@Override
+	public int getOrder() {
+		return 0;
+	}
+
 	private Set<String> getBeanNames(ListableBeanFactory beanFactory) {
 		Set<String> names = getBeanNames(beanFactory, this.beanClass);
 		if (this.factoryBeanClass != null) {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/AbstractDependsOnBeanFactoryPostProcessorTests.java

@@ -73,6 +73,11 @@ public class AbstractDependsOnBeanFactoryPostProcessorTests {
 		}
 	}
 
+	@Test
+	public void postProcessorHasADefaultOrderOfZero() {
+		assertThat(new FooDependsOnBarTypePostProcessor().getOrder()).isEqualTo(0);
+	}
+
 	private void assertThatFooDependsOnBar(AssertableApplicationContext context) {
 		ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
 		assertThat(getBeanDefinition("foo", beanFactory).getDependsOn()).containsExactly("bar", "barFactoryBean");