Prevent @Bean method being public if it should not be

buildSrc/src/main/java/org/springframework/boot/build/architecture/ArchitectureRules.java

@@ -98,6 +98,7 @@ static List<ArchRule> standard() {
 		rules.add(methodLevelConfigurationPropertiesShouldNotSpecifyOnlyPrefixAttribute());
 		rules.add(conditionsShouldNotBePublic());
 		rules.add(allConfigurationPropertiesBindingBeanMethodsShouldBeStatic());
+		rules.add(allConfigurationMethodsShouldNotBePublicIfReturnTypeOrParameterTypeIsNotPublic());
 		return List.copyOf(rules);
 	}
 
@@ -319,6 +320,30 @@ private static ArchRule allConfigurationPropertiesBindingBeanMethodsShouldBeStat
 			.allowEmptyShould(true);
 	}
 
+	private static ArchRule allConfigurationMethodsShouldNotBePublicIfReturnTypeOrParameterTypeIsNotPublic() {
+		return methodsThatAreAnnotatedWith("org.springframework.context.annotation.Bean")
+			.should(check("not be public if return type is not public or any of parameter types is not public",
+					ArchitectureRules::configurationMethodsShouldNotBePublicIfReturnTypeOrParameterTypeIsNotPublic))
+			.allowEmptyShould(true);
+	}
+
+	private static void configurationMethodsShouldNotBePublicIfReturnTypeOrParameterTypeIsNotPublic(JavaMethod item,
+			ConditionEvents events) {
+		if (!item.getModifiers().contains(JavaModifier.PUBLIC)) {
+			return;
+		}
+		boolean violated = !item.getReturnType().toErasure().getModifiers().contains(JavaModifier.PUBLIC);
+		if (!violated) {
+			violated = item.getParameterTypes()
+				.stream()
+				.anyMatch((parameterType) -> !parameterType.toErasure().getModifiers().contains(JavaModifier.PUBLIC));
+		}
+		if (violated) {
+			addViolation(events, item, item.getDescription()
+					+ " should not be public if return type is not public or any of parameter types is not public");
+		}
+	}
+
 	private static boolean containsOnlySingleType(JavaType[] types, JavaType type) {
 		return types.length == 1 && type.equals(types[0]);
 	}

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/availability/AvailabilityProbesAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -59,7 +59,7 @@ public ReadinessStateHealthIndicator readinessStateHealthIndicator(
 	}
 
 	@Bean
-	public AvailabilityProbesHealthEndpointGroupsPostProcessor availabilityProbesHealthEndpointGroupsPostProcessor(
+	AvailabilityProbesHealthEndpointGroupsPostProcessor availabilityProbesHealthEndpointGroupsPostProcessor(
 			Environment environment) {
 		return new AvailabilityProbesHealthEndpointGroupsPostProcessor(environment);
 	}

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/cloudfoundry/reactive/ReactiveCloudFoundryActuatorAutoConfiguration.java

@@ -107,7 +107,7 @@ public CloudFoundryInfoEndpointWebExtension cloudFoundryInfoEndpointWebExtension
 
 	@Bean
 	@SuppressWarnings("removal")
-	public CloudFoundryWebFluxEndpointHandlerMapping cloudFoundryWebFluxEndpointHandlerMapping(
+	CloudFoundryWebFluxEndpointHandlerMapping cloudFoundryWebFluxEndpointHandlerMapping(
 			ParameterValueMapper parameterMapper, EndpointMediaTypes endpointMediaTypes,
 			WebClient.Builder webClientBuilder,
 			org.springframework.boot.actuate.endpoint.web.annotation.ControllerEndpointsSupplier controllerEndpointsSupplier,

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/cloudfoundry/servlet/CloudFoundryActuatorAutoConfiguration.java

@@ -111,7 +111,7 @@ public CloudFoundryInfoEndpointWebExtension cloudFoundryInfoEndpointWebExtension
 
 	@Bean
 	@SuppressWarnings("removal")
-	public CloudFoundryWebEndpointServletHandlerMapping cloudFoundryWebEndpointServletHandlerMapping(
+	CloudFoundryWebEndpointServletHandlerMapping cloudFoundryWebEndpointServletHandlerMapping(
 			ParameterValueMapper parameterMapper, EndpointMediaTypes endpointMediaTypes,
 			RestTemplateBuilder restTemplateBuilder,
 			org.springframework.boot.actuate.endpoint.web.annotation.ServletEndpointsSupplier servletEndpointsSupplier,

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/endpoint/jmx/JmxEndpointAutoConfiguration.java

@@ -92,7 +92,7 @@ public JmxEndpointDiscoverer jmxAnnotationEndpointDiscoverer(ParameterValueMappe
 
 	@Bean
 	@ConditionalOnMissingBean(value = EndpointObjectNameFactory.class, search = SearchStrategy.CURRENT)
-	public DefaultEndpointObjectNameFactory endpointObjectNameFactory(MBeanServer mBeanServer) {
+	DefaultEndpointObjectNameFactory endpointObjectNameFactory(MBeanServer mBeanServer) {
 		String contextId = ObjectUtils.getIdentityHexString(this.applicationContext);
 		return new DefaultEndpointObjectNameFactory(this.properties, this.jmxProperties, mBeanServer, contextId);
 	}

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/MetricsAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -56,7 +56,7 @@ public Clock micrometerClock() {
 	}
 
 	@Bean
-	public static MeterRegistryPostProcessor meterRegistryPostProcessor(ApplicationContext applicationContext,
+	static MeterRegistryPostProcessor meterRegistryPostProcessor(ApplicationContext applicationContext,
 			ObjectProvider<MetricsProperties> metricsProperties,
 			ObjectProvider<MeterRegistryCustomizer<?>> meterRegistryCustomizers,
 			ObjectProvider<MeterFilter> meterFilters, ObjectProvider<MeterBinder> meterBinders) {

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/amqp/RabbitMetricsAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -44,7 +44,7 @@
 public class RabbitMetricsAutoConfiguration {
 
 	@Bean
-	public static RabbitConnectionFactoryMetricsPostProcessor rabbitConnectionFactoryMetricsPostProcessor(
+	static RabbitConnectionFactoryMetricsPostProcessor rabbitConnectionFactoryMetricsPostProcessor(
 			ApplicationContext applicationContext) {
 		return new RabbitConnectionFactoryMetricsPostProcessor(applicationContext);
 	}

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/data/RepositoryMetricsAutoConfiguration.java

@@ -72,7 +72,7 @@ public MetricsRepositoryMethodInvocationListener metricsRepositoryMethodInvocati
 	}
 
 	@Bean
-	public static MetricsRepositoryMethodInvocationListenerBeanPostProcessor metricsRepositoryMethodInvocationListenerBeanPostProcessor(
+	static MetricsRepositoryMethodInvocationListenerBeanPostProcessor metricsRepositoryMethodInvocationListenerBeanPostProcessor(
 			ObjectProvider<MetricsRepositoryMethodInvocationListener> metricsRepositoryMethodInvocationListener) {
 		return new MetricsRepositoryMethodInvocationListenerBeanPostProcessor(
 				SingletonSupplier.of(metricsRepositoryMethodInvocationListener::getObject));

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/web/annotation/AbstractWebEndpointIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -725,7 +725,7 @@ private void load(Consumer<T> contextCustomizer, String endpointPath,
 	protected static class TestEndpointConfiguration {
 
 		@Bean
-		public TestEndpoint testEndpoint(EndpointDelegate endpointDelegate) {
+		TestEndpoint testEndpoint(EndpointDelegate endpointDelegate) {
 			return new TestEndpoint(endpointDelegate);
 		}
 
@@ -846,7 +846,7 @@ NullDeleteResponseEndpoint nullDeleteResponseEndpoint() {
 	protected static class ResourceEndpointConfiguration {
 
 		@Bean
-		public ResourceEndpoint resourceEndpoint() {
+		ResourceEndpoint resourceEndpoint() {
 			return new ResourceEndpoint();
 		}
 

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

@@ -69,7 +69,7 @@ public CacheManagerCustomizers cacheManagerCustomizers(ObjectProvider<CacheManag
 	}
 
 	@Bean
-	public CacheManagerValidator cacheAutoConfigurationValidator(CacheProperties cacheProperties,
+	CacheManagerValidator cacheAutoConfigurationValidator(CacheProperties cacheProperties,
 			ObjectProvider<CacheManager> cacheManager) {
 		return new CacheManagerValidator(cacheProperties, cacheManager);
 	}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/rest/RepositoryRestMvcAutoConfiguration.java

@@ -56,7 +56,7 @@
 public class RepositoryRestMvcAutoConfiguration {
 
 	@Bean
-	public SpringBootRepositoryRestConfigurer springBootRepositoryRestConfigurer(
+	SpringBootRepositoryRestConfigurer springBootRepositoryRestConfigurer(
 			ObjectProvider<Jackson2ObjectMapperBuilder> objectMapperBuilder, RepositoryRestProperties properties) {
 		return new SpringBootRepositoryRestConfigurer(objectMapperBuilder.getIfAvailable(), properties);
 	}

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

@@ -113,12 +113,12 @@ public class FlywayAutoConfiguration {
 
 	@Bean
 	@ConfigurationPropertiesBinding
-	public static StringOrNumberToMigrationVersionConverter stringOrNumberMigrationVersionConverter() {
+	static StringOrNumberToMigrationVersionConverter stringOrNumberMigrationVersionConverter() {
 		return new StringOrNumberToMigrationVersionConverter();
 	}
 
 	@Bean
-	public FlywaySchemaManagementProvider flywayDefaultDdlModeProvider(ObjectProvider<Flyway> flyways) {
+	FlywaySchemaManagementProvider flywayDefaultDdlModeProvider(ObjectProvider<Flyway> flyways) {
 		return new FlywaySchemaManagementProvider(flyways);
 	}
 

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/graphql/rsocket/GraphQlRSocketAutoConfiguration.java

@@ -62,7 +62,7 @@ public GraphQlRSocketHandler graphQlRSocketHandler(ExecutionGraphQlService graph
 
 	@Bean
 	@ConditionalOnMissingBean
-	public GraphQlRSocketController graphQlRSocketController(GraphQlRSocketHandler handler) {
+	GraphQlRSocketController graphQlRSocketController(GraphQlRSocketHandler handler) {
 		return new GraphQlRSocketController(handler);
 	}
 

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

@@ -60,7 +60,7 @@ public Gson gson(GsonBuilder gsonBuilder) {
 	}
 
 	@Bean
-	public StandardGsonBuilderCustomizer standardGsonBuilderCustomizer(GsonProperties gsonProperties) {
+	StandardGsonBuilderCustomizer standardGsonBuilderCustomizer(GsonProperties gsonProperties) {
 		return new StandardGsonBuilderCustomizer(gsonProperties);
 	}
 

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

@@ -82,8 +82,7 @@
 public class LiquibaseAutoConfiguration {
 
 	@Bean
-	public LiquibaseSchemaManagementProvider liquibaseDefaultDdlModeProvider(
-			ObjectProvider<SpringLiquibase> liquibases) {
+	LiquibaseSchemaManagementProvider liquibaseDefaultDdlModeProvider(ObjectProvider<SpringLiquibase> liquibases) {
 		return new LiquibaseSchemaManagementProvider(liquibases);
 	}
 

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/HttpEncodingAutoConfiguration.java

@@ -64,7 +64,7 @@ public CharacterEncodingFilter characterEncodingFilter() {
 	}
 
 	@Bean
-	public LocaleCharsetMappingsCustomizer localeCharsetMappingsCustomizer() {
+	LocaleCharsetMappingsCustomizer localeCharsetMappingsCustomizer() {
 		return new LocaleCharsetMappingsCustomizer(this.properties);
 	}
 

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration.java

@@ -202,7 +202,7 @@ public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer,
 
 		private ServletContext servletContext;
 
-		public WebMvcAutoConfigurationAdapter(WebProperties webProperties, WebMvcProperties mvcProperties,
+		WebMvcAutoConfigurationAdapter(WebProperties webProperties, WebMvcProperties mvcProperties,
 				ListableBeanFactory beanFactory, ObjectProvider<HttpMessageConverters> messageConvertersProvider,
 				ObjectProvider<ResourceHandlerRegistrationCustomizer> resourceHandlerRegistrationCustomizerProvider,
 				ObjectProvider<DispatcherServletPath> dispatcherServletPath,
@@ -383,7 +383,7 @@ public static RequestContextFilter requestContextFilter() {
 	 */
 	@Configuration(proxyBeanMethods = false)
 	@EnableConfigurationProperties(WebProperties.class)
-	public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration implements ResourceLoaderAware {
+	static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration implements ResourceLoaderAware {
 
 		private final Resources resourceProperties;
 
@@ -397,7 +397,7 @@ public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfigurat
 
 		private ResourceLoader resourceLoader;
 
-		public EnableWebMvcConfiguration(WebMvcProperties mvcProperties, WebProperties webProperties,
+		EnableWebMvcConfiguration(WebMvcProperties mvcProperties, WebProperties webProperties,
 				ObjectProvider<WebMvcRegistrations> mvcRegistrationsProvider,
 				ObjectProvider<ResourceHandlerRegistrationCustomizer> resourceHandlerRegistrationCustomizerProvider,
 				ListableBeanFactory beanFactory) {
@@ -420,14 +420,14 @@ protected RequestMappingHandlerAdapter createRequestMappingHandlerAdapter() {
 		}
 
 		@Bean
-		public WelcomePageHandlerMapping welcomePageHandlerMapping(ApplicationContext applicationContext,
+		WelcomePageHandlerMapping welcomePageHandlerMapping(ApplicationContext applicationContext,
 				FormattingConversionService mvcConversionService, ResourceUrlProvider mvcResourceUrlProvider) {
 			return createWelcomePageHandlerMapping(applicationContext, mvcConversionService, mvcResourceUrlProvider,
 					WelcomePageHandlerMapping::new);
 		}
 
 		@Bean
-		public WelcomePageNotAcceptableHandlerMapping welcomePageNotAcceptableHandlerMapping(
+		WelcomePageNotAcceptableHandlerMapping welcomePageNotAcceptableHandlerMapping(
 				ApplicationContext applicationContext, FormattingConversionService mvcConversionService,
 				ResourceUrlProvider mvcResourceUrlProvider) {
 			return createWelcomePageHandlerMapping(applicationContext, mvcConversionService, mvcResourceUrlProvider,

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/error/ErrorMvcAutoConfiguration.java

@@ -110,12 +110,12 @@ public BasicErrorController basicErrorController(ErrorAttributes errorAttributes
 	}
 
 	@Bean
-	public ErrorPageCustomizer errorPageCustomizer(DispatcherServletPath dispatcherServletPath) {
+	ErrorPageCustomizer errorPageCustomizer(DispatcherServletPath dispatcherServletPath) {
 		return new ErrorPageCustomizer(this.serverProperties, dispatcherServletPath);
 	}
 
 	@Bean
-	public static PreserveErrorControllerTargetClassPostProcessor preserveErrorControllerTargetClassPostProcessor() {
+	static PreserveErrorControllerTargetClassPostProcessor preserveErrorControllerTargetClassPostProcessor() {
 		return new PreserveErrorControllerTargetClassPostProcessor();
 	}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -84,7 +84,7 @@ public ServletRegistrationBean<MessageDispatcherServlet> messageDispatcherServle
 	@Bean
 	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
 	@Conditional(OnWsdlLocationsCondition.class)
-	public static WsdlDefinitionBeanFactoryPostProcessor wsdlDefinitionBeanFactoryPostProcessor() {
+	static WsdlDefinitionBeanFactoryPostProcessor wsdlDefinitionBeanFactoryPostProcessor() {
 		return new WsdlDefinitionBeanFactoryPostProcessor();
 	}
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/condition/scan/ScannedFactoryBeanWithBeanMethodArgumentsConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -29,12 +29,12 @@
 public class ScannedFactoryBeanWithBeanMethodArgumentsConfiguration {
 
 	@Bean
-	public Foo foo() {
+	Foo foo() {
 		return new Foo();
 	}
 
 	@Bean
-	public ScanFactoryBean exampleBeanFactoryBean(Foo foo) {
+	ScanFactoryBean exampleBeanFactoryBean(Foo foo) {
 		return new ScanFactoryBean("foo");
 	}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -77,15 +77,15 @@ public String message() {
 	static class TestConfiguration {
 
 		@Configuration(proxyBeanMethods = false)
-		public class JerseyConfiguration {
+		static class JerseyConfiguration {
 
 			@Bean
-			public TestApplication testApplication() {
+			TestApplication testApplication() {
 				return new TestApplication();
 			}
 
 			@Bean
-			public ResourceConfig conf(TestApplication app) {
+			ResourceConfig conf(TestApplication app) {
 				ResourceConfig config = ResourceConfig.forApplication(app);
 				config.register(TestController.class);
 				return config;

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -142,7 +142,7 @@ void sslBundleWithoutClassPathPrefix() {
 	public static class CustomSslBundleConfiguration {
 
 		@Bean
-		public SslBundleRegistrar customSslBundlesRegistrar(CustomSslProperties properties) {
+		SslBundleRegistrar customSslBundlesRegistrar(CustomSslProperties properties) {
 			return new CustomSslBundlesRegistrar(properties);
 		}
 

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/actuator/metrics/registeringcustom/MyMeterBinderConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -24,7 +24,7 @@
 public class MyMeterBinderConfiguration {
 
 	@Bean
-	public MeterBinder queueSize(Queue queue) {
+	MeterBinder queueSize(Queue queue) {
 		return (registry) -> Gauge.builder("queueSize", queue::size).register(registry);
 	}
 

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/features/developingautoconfiguration/conditionannotations/classconditions/MyAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -34,7 +34,7 @@ public static class SomeServiceConfiguration {
 
 		@Bean
 		@ConditionalOnMissingBean
-		public SomeService someService() {
+		SomeService someService() {
 			return new SomeService();
 		}
 

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/features/externalconfig/typesafeconfigurationproperties/thirdpartyconfiguration/ThirdPartyConfiguration.java

@@ -25,7 +25,7 @@ public class ThirdPartyConfiguration {
 
 	@Bean
 	@ConfigurationProperties("another")
-	public AnotherComponent anotherComponent() {
+	AnotherComponent anotherComponent() {
 		return new AnotherComponent();
 	}