Stop deferring JPA bootstrap mode by default

This commit changes the default value of bootstrap-mode to "default"
rather than "deferred" so that the JPA infrastructure starts in the
main thread rather than asynchronously.

Closes gh-24249

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/jpa/JpaRepositoriesAutoConfiguration.java

@@ -96,13 +96,12 @@ public class JpaRepositoriesAutoConfiguration {
 		}
 
 		@ConditionalOnProperty(prefix = "spring.data.jpa.repositories", name = "bootstrap-mode",
-				havingValue = "deferred", matchIfMissing = true)
+				havingValue = "deferred")
 		static class DeferredBootstrapMode {
 
 		}
 
-		@ConditionalOnProperty(prefix = "spring.data.jpa.repositories", name = "bootstrap-mode", havingValue = "lazy",
+		@ConditionalOnProperty(prefix = "spring.data.jpa.repositories", name = "bootstrap-mode", havingValue = "lazy")
-				matchIfMissing = false)
 		static class LazyBootstrapMode {
 
 		}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/jpa/JpaRepositoriesRegistrar.java

@@ -57,7 +57,7 @@ class JpaRepositoriesRegistrar extends AbstractRepositoryConfigurationSourceSupp
 
 	@Override
 	protected BootstrapMode getBootstrapMode() {
-		return (this.bootstrapMode == null) ? BootstrapMode.DEFERRED : this.bootstrapMode;
+		return (this.bootstrapMode == null) ? BootstrapMode.DEFAULT : this.bootstrapMode;
 	}
 
 	@Override

spring-boot-project/spring-boot-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -622,7 +622,7 @@
       "name": "spring.data.jpa.repositories.bootstrap-mode",
       "type": "org.springframework.data.repository.config.BootstrapMode",
       "description": "Bootstrap mode for JPA repositories.",
-      "defaultValue": "deferred"
+      "defaultValue": "default"
     },
     {
       "name": "spring.data.jpa.repositories.enabled",

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/data/jpa/JpaRepositoriesAutoConfigurationTests.java

@@ -126,13 +126,12 @@ class JpaRepositoriesAutoConfigurationTests {
 	}
 
 	@Test
-	void bootstrapModeIsDeferredByDefault() {
+	void bootstrapModeIsDefaultByDefault() {
 		this.contextRunner.withUserConfiguration(MultipleAsyncTaskExecutorConfiguration.class)
 				.withConfiguration(AutoConfigurations.of(TaskExecutionAutoConfiguration.class,
 						TaskSchedulingAutoConfiguration.class))
 				.run((context) -> assertThat(
-						context.getBean(LocalContainerEntityManagerFactoryBean.class).getBootstrapExecutor())
+						context.getBean(LocalContainerEntityManagerFactoryBean.class).getBootstrapExecutor()).isNull());
-								.isEqualTo(context.getBean("applicationTaskExecutor")));
 	}
 
 	@Configuration(proxyBeanMethods = false)

spring-boot-project/spring-boot-docs/src/docs/asciidoc/spring-boot-features.adoc

@@ -3839,6 +3839,8 @@ To enable deferred or lazy bootstrapping, set the configprop:spring.data.jpa.rep
 When using deferred or lazy bootstrapping, the auto-configured `EntityManagerFactoryBuilder` will use the context's `AsyncTaskExecutor`, if any, as the bootstrap executor.
 If more than one exists, the one named `applicationTaskExecutor` will be used.
 
+NOTE: When using deferred or lazy bootstraping, make sure to defer any access to the JPA infrastructure after the application context bootstrap phase.
+
 TIP: We have barely scratched the surface of Spring Data JPA.
 For complete details, see the {spring-data-jdbc-docs}[Spring Data JPA reference documentation].
 

spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/orm/jpa/DataJpaTest.java

@@ -103,11 +103,11 @@ public @interface DataJpaTest {
 
 	/**
 	 * The {@link BootstrapMode} for the test repository support. Defaults to
-	 * {@link BootstrapMode#LAZY}.
+	 * {@link BootstrapMode#DEFAULT}.
 	 * @return the {@link BootstrapMode} to use for testing the repository
 	 */
 	@PropertyMapping("spring.data.jpa.repositories.bootstrap-mode")
-	BootstrapMode bootstrapMode() default BootstrapMode.LAZY;
+	BootstrapMode bootstrapMode() default BootstrapMode.DEFAULT;
 
 	/**
 	 * Determines if default filtering should be used with

spring-boot-project/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/orm/jpa/DataJpaTestIntegrationTests.java

@@ -109,9 +109,9 @@ class DataJpaTestIntegrationTests {
 	}
 
 	@Test
-	void bootstrapModeIsLazyByDefault() {
+	void bootstrapModeIsDefaultByDefault() {
 		assertThat(this.applicationContext.getEnvironment().getProperty("spring.data.jpa.repositories.bootstrap-mode"))
-				.isEqualTo(BootstrapMode.LAZY.name());
+				.isEqualTo(BootstrapMode.DEFAULT.name());
 	}
 
 }