Recommend using defaultCandidate=false on qualified beans

Closes gh-42831

Author: wilkinsona

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

@@ -536,13 +536,12 @@ private Job mockJob(String name) {
 	static class BatchDataSourceConfiguration {
 
 		@Bean
-		@Primary
 		DataSource normalDataSource() {
 			return DataSourceBuilder.create().url("jdbc:hsqldb:mem:normal").username("sa").build();
 		}
 
 		@BatchDataSource
-		@Bean
+		@Bean(defaultCandidate = false)
 		DataSource batchDataSource() {
 			return DataSourceBuilder.create().url("jdbc:hsqldb:mem:batchdatasource").username("sa").build();
 		}
@@ -564,7 +563,7 @@ PlatformTransactionManager normalTransactionManager() {
 		}
 
 		@BatchTransactionManager
-		@Bean
+		@Bean(defaultCandidate = false)
 		PlatformTransactionManager batchTransactionManager() {
 			return mock(PlatformTransactionManager.class);
 		}
@@ -575,13 +574,12 @@ PlatformTransactionManager batchTransactionManager() {
 	static class BatchTaskExecutorConfiguration {
 
 		@Bean
-		@Primary
 		TaskExecutor taskExecutor() {
 			return new SyncTaskExecutor();
 		}
 
-		@Bean
 		@BatchTaskExecutor
+		@Bean(defaultCandidate = false)
 		TaskExecutor batchTaskExecutor() {
 			return new SimpleAsyncTaskExecutor();
 		}

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

@@ -317,7 +317,8 @@ void schemaManagementProviderDetectsDataSource() {
 			.run((context) -> {
 				FlywaySchemaManagementProvider schemaManagementProvider = context
 					.getBean(FlywaySchemaManagementProvider.class);
-				assertThat(schemaManagementProvider.getSchemaManagement(context.getBean(DataSource.class)))
+				assertThat(schemaManagementProvider
+					.getSchemaManagement(context.getBean("normalDataSource", DataSource.class)))
 					.isEqualTo(SchemaManagement.UNMANAGED);
 				assertThat(schemaManagementProvider
 					.getSchemaManagement(context.getBean("flywayDataSource", DataSource.class)))
@@ -928,13 +929,12 @@ private ContextConsumer<AssertableApplicationContext> validateFlywayTeamsPropert
 	static class FlywayDataSourceConfiguration {
 
 		@Bean
-		@Primary
 		DataSource normalDataSource() {
 			return DataSourceBuilder.create().url("jdbc:hsqldb:mem:normal").username("sa").build();
 		}
 
 		@FlywayDataSource
-		@Bean
+		@Bean(defaultCandidate = false)
 		DataSource flywayDataSource() {
 			return DataSourceBuilder.create().url("jdbc:hsqldb:mem:flywaytest").username("sa").build();
 		}
@@ -955,7 +955,7 @@ DataSource secondDataSource() {
 		}
 
 		@FlywayDataSource
-		@Bean
+		@Bean(defaultCandidate = false)
 		DataSource flywayDataSource() {
 			return DataSourceBuilder.create().url("jdbc:hsqldb:mem:flywaytest").username("sa").build();
 		}

spring-boot-project/spring-boot-docs/src/docs/antora/modules/how-to/pages/batch.adoc

@@ -12,7 +12,7 @@ This section addresses those questions.
 By default, batch applications require a `DataSource` to store job details.
 Spring Batch expects a single `DataSource` by default.
 To have it use a `DataSource` other than the application’s main `DataSource`, declare a `DataSource` bean, annotating its `@Bean` method with `@BatchDataSource`.
-If you do so and want two data sources, remember to mark the other one `@Primary`.
+If you do so and want two data sources (for example by retaining the main auto-configured `DataSource`), set the `defaultCandidate` attribute of the `@Bean` annotation to `false`.
 To take greater control, add `@EnableBatchProcessing` to one of your `@Configuration` classes or extend `DefaultBatchConfiguration`.
 See the API documentation of javadoc:{url-spring-batch-javadoc}/org.springframework.batch.core.configuration.annotation.EnableBatchProcessing[format=annotation]
 and javadoc:{url-spring-batch-javadoc}/org.springframework.batch.core.configuration.support.DefaultBatchConfiguration[] for more details.
@@ -24,16 +24,16 @@ For more info about Spring Batch, see the {url-spring-batch-site}[Spring Batch p
 [[howto.batch.specifying-a-transaction-manager]]
 == Specifying a Batch Transaction Manager
 
-Similar to xref:batch.adoc#howto.batch.specifying-a-data-source[], you can define a `PlatformTransactionManager` for use in the batch processing by marking it as `@BatchTransactionManager`.
-If you do so and want two transaction managers, remember to mark the other one as `@Primary`.
+Similar to xref:batch.adoc#howto.batch.specifying-a-data-source[], you can define a `PlatformTransactionManager` for use in batch processing by annotating its `@Bean` method with `@BatchTransactionManager`.
+If you do so and want two transaction managers (for example by retaining the auto-configured `PlatformTransactionManager`), set the `defaultCandidate` attribute of the `@Bean` annotation to `false`.
 
 
 
 [[howto.batch.specifying-a-task-executor]]
 == Specifying a Batch Task Executor
 
-Similar to xref:batch.adoc#howto.batch.specifying-a-data-source[], you can define a `TaskExecutor` for use in the batch processing by marking it as `@BatchTaskExecutor`.
-If you do so and want two task executors, remember to mark the other one as `@Primary`.
+Similar to xref:batch.adoc#howto.batch.specifying-a-data-source[], you can define a `TaskExecutor` for use in batch processing by annotating its `@Bean` method with `@BatchTaskExecutor`.
+If you do so and want two task executors (for example by retaining the auto-configured `TaskExecutor`), set the `defaultCandidate` attribute of the `@Bean` annotation to `false`.
 
 
 

spring-boot-project/spring-boot-docs/src/docs/antora/modules/how-to/pages/data-initialization.adoc

@@ -146,7 +146,7 @@ Beans that implement the deprecated `FlywayCallback` interface can also be detec
 
 By default, Flyway autowires the (`@Primary`) `DataSource` in your context and uses that for migrations.
 If you like to use a different `DataSource`, you can create one and mark its `@Bean` as `@FlywayDataSource`.
-If you do so and want two data sources, remember to create another one and mark it as `@Primary`.
+If you do so and want two data sources (for example by retaining the main auto-configured `DataSource`), remember to set the `defaultCandidate` attribute of the `@Bean` annotation to `false`.
 Alternatively, you can use Flyway's native `DataSource` by setting `spring.flyway.[url,user,password]` in external properties.
 Setting either `spring.flyway.url` or `spring.flyway.user` is sufficient to cause Flyway to use its own `DataSource`.
 If any of the three properties has not been set, the value of its equivalent `spring.datasource` property will be used.
@@ -184,7 +184,7 @@ In addition to YAML, Liquibase also supports JSON, XML, and SQL change log forma
 
 By default, Liquibase autowires the (`@Primary`) `DataSource` in your context and uses that for migrations.
 If you need to use a different `DataSource`, you can create one and mark its `@Bean` as `@LiquibaseDataSource`.
-If you do so and you want two data sources, remember to create another one and mark it as `@Primary`.
+If you do so and want two data sources (for example by retaining the main auto-configured `DataSource`), remember to set the `defaultCandidate` attribute of the `@Bean` annotation to `false`.
 Alternatively, you can use Liquibase's native `DataSource` by setting `spring.liquibase.[driver-class-name,url,user,password]` in external properties.
 Setting either `spring.liquibase.url` or `spring.liquibase.user` is sufficient to cause Liquibase to use its own `DataSource`.
 If any of the three properties has not been set, the value of its equivalent `spring.datasource` property will be used.