DATAJDBC-204 - Polishing.

Extracted ApplicationContext and Repository construction into method in order to make the actual test stand out more.
Split a test in two.
JavaDoc.
Code formatting.
Removed access modifiers in tests.

src/main/java/org/springframework/data/jdbc/domain/support/JdbcAuditingEventListener.java

@@ -19,30 +19,22 @@ import org.springframework.beans.factory.ObjectFactory;
 import org.springframework.context.ApplicationListener;
 import org.springframework.data.auditing.AuditingHandler;
 import org.springframework.data.jdbc.mapping.event.BeforeSaveEvent;
+import org.springframework.data.jdbc.repository.config.EnableJdbcAuditing;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
  * Spring JDBC event listener to capture auditing information on persisting and updating entities.
  * <p>
- * You can enable this class just a matter of activating auditing using {@link org.springframework.data.jdbc.repository.config.EnableJdbcAuditing} in your Spring config:
- *
- * <pre>
- * &#064;Configuration
- * &#064;EnableJdbcRepositories
- * &#064;EnableJdbcAuditing
- * class JdbcRepositoryConfig {
- * }
- * </pre>
+ * An instance of this class gets registered when you apply {@link EnableJdbcAuditing} to your Spring config.
  *
  * @author Kazuki Shimizu
- * @see org.springframework.data.jdbc.repository.config.EnableJdbcAuditing
+ * @see EnableJdbcAuditing
  * @since 1.0
  */
 public class JdbcAuditingEventListener implements ApplicationListener<BeforeSaveEvent> {
 
-	@Nullable
-	private AuditingHandler handler;
+	@Nullable private AuditingHandler handler;
 
 	/**
 	 * Configures the {@link AuditingHandler} to be used to set the current auditor on the domain types touched.
@@ -50,18 +42,24 @@ public class JdbcAuditingEventListener implements ApplicationListener<BeforeSave
 	 * @param auditingHandler must not be {@literal null}.
 	 */
 	public void setAuditingHandler(ObjectFactory<AuditingHandler> auditingHandler) {
+
 		Assert.notNull(auditingHandler, "AuditingHandler must not be null!");
+
 		this.handler = auditingHandler.getObject();
 	}
 
 	/**
 	 * {@inheritDoc}
+	 * 
 	 * @param event a notification event for indicating before save
 	 */
 	@Override
 	public void onApplicationEvent(BeforeSaveEvent event) {
+
 		if (handler != null) {
+
 			event.getOptionalEntity().ifPresent(entity -> {
+
 				if (event.getId().getOptionalValue().isPresent()) {
 					handler.markModified(entity);
 				} else {
@@ -70,5 +68,4 @@ public class JdbcAuditingEventListener implements ApplicationListener<BeforeSave
 			});
 		}
 	}
-
 }

src/main/java/org/springframework/data/jdbc/repository/config/EnableJdbcAuditing.java

@@ -29,22 +29,6 @@ import org.springframework.data.domain.AuditorAware;
 /**
  * Annotation to enable auditing in JDBC via annotation configuration.
  *
- * If you use the auditing feature, you should be configures beans of Spring Data JDBC
- * using {@link org.springframework.data.jdbc.repository.config.EnableJdbcRepositories} in your Spring config:
- *
- * <pre>
- * &#064;Configuration
- * &#064;EnableJdbcRepositories
- * &#064;EnableJdbcAuditing
- * class JdbcRepositoryConfig {
- * }
- * </pre>
- *
- * <p>
- * Note: This feature cannot use to a entity that implements {@link org.springframework.data.domain.Auditable}
- * because the Spring Data JDBC does not support an {@link java.util.Optional} property yet.
- * </p>
- *
  * @see EnableJdbcRepositories
  * @author Kazuki Shimizu
  * @since 1.0

src/main/java/org/springframework/data/jdbc/repository/config/JdbcAuditingRegistrar.java

@@ -27,7 +27,8 @@ import org.springframework.data.config.ParsingUtils;
 import org.springframework.data.jdbc.domain.support.JdbcAuditingEventListener;
 
 /**
- * {@link ImportBeanDefinitionRegistrar} to enable {@link EnableJdbcAuditing} annotation.
+ * {@link ImportBeanDefinitionRegistrar} which registers additional beans in order to enable auditing via the
+ * {@link EnableJdbcAuditing} annotation.
  *
  * @see EnableJdbcAuditing
  * @author Kazuki Shimizu
@@ -37,8 +38,9 @@ class JdbcAuditingRegistrar extends AuditingBeanDefinitionRegistrarSupport {
 
 	/**
 	 * {@inheritDoc}
+	 * 
 	 * @return return the {@link EnableJdbcAuditing}
-	 * @see org.springframework.data.auditing.config.AuditingBeanDefinitionRegistrarSupport#getAnnotation()
+	 * @see AuditingBeanDefinitionRegistrarSupport#getAnnotation()
 	 */
 	@Override
 	protected Class<? extends Annotation> getAnnotation() {
@@ -47,8 +49,9 @@ class JdbcAuditingRegistrar extends AuditingBeanDefinitionRegistrarSupport {
 
 	/**
 	 * {@inheritDoc}
+	 * 
 	 * @return return "{@literal jdbcAuditingHandler}"
-	 * @see org.springframework.data.auditing.config.AuditingBeanDefinitionRegistrarSupport#getAuditingHandlerBeanName()
+	 * @see AuditingBeanDefinitionRegistrarSupport#getAuditingHandlerBeanName()
 	 */
 	@Override
 	protected String getAuditingHandlerBeanName() {
@@ -61,22 +64,25 @@ class JdbcAuditingRegistrar extends AuditingBeanDefinitionRegistrarSupport {
 	 */
 	@Override
 	protected BeanDefinitionBuilder getAuditHandlerBeanDefinitionBuilder(AuditingConfiguration configuration) {
+
 		BeanDefinitionBuilder builder = super.getAuditHandlerBeanDefinitionBuilder(configuration);
 		return builder.addConstructorArgReference("jdbcMappingContext");
 	}
 
 	/**
-	 * Register the bean definition of {@link JdbcAuditingEventListener}.
-	 * {@inheritDoc}
-	 * @see org.springframework.data.auditing.config.AuditingBeanDefinitionRegistrarSupport#registerAuditListenerBeanDefinition(BeanDefinition, BeanDefinitionRegistry)
+	 * Register the bean definition of {@link JdbcAuditingEventListener}. {@inheritDoc}
+	 * 
+	 * @see AuditingBeanDefinitionRegistrarSupport#registerAuditListenerBeanDefinition(BeanDefinition,
+	 *      BeanDefinitionRegistry)
 	 */
 	@Override
 	protected void registerAuditListenerBeanDefinition(BeanDefinition auditingHandlerDefinition,
-													   BeanDefinitionRegistry registry) {
+			BeanDefinitionRegistry registry) {
+
 		Class<?> listenerClass = JdbcAuditingEventListener.class;
 		BeanDefinitionBuilder builder = BeanDefinitionBuilder.rootBeanDefinition(listenerClass);
 		builder.addPropertyValue("auditingHandler",
-			ParsingUtils.getObjectFactoryBeanDefinition(getAuditingHandlerBeanName(), null));
+				ParsingUtils.getObjectFactoryBeanDefinition(getAuditingHandlerBeanName(), null));
 		registerInfrastructureBeanWithId(builder.getRawBeanDefinition(), listenerClass.getName(), registry);
 	}