Rename BeanInstantiationContributor to Contribution

This commit polishes the contribution model where an AOT contributing
bean post processor can return a contribution, rather than a
contributor. This makes it easier to return `null` if no contribution
can be produced now that it is named this way.

See gh-28047

spring-beans/src/main/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessor.java

@@ -57,7 +57,7 @@ import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.beans.factory.config.DependencyDescriptor;
 import org.springframework.beans.factory.config.SmartInstantiationAwareBeanPostProcessor;
 import org.springframework.beans.factory.generator.AotContributingBeanPostProcessor;
-import org.springframework.beans.factory.generator.BeanInstantiationContributor;
+import org.springframework.beans.factory.generator.BeanInstantiationContribution;
 import org.springframework.beans.factory.generator.InjectionGenerator;
 import org.springframework.beans.factory.support.LookupOverride;
 import org.springframework.beans.factory.support.MergedBeanDefinitionPostProcessor;
@@ -268,12 +268,12 @@ public class AutowiredAnnotationBeanPostProcessor implements SmartInstantiationA
 	}
 
 	@Override
-	public BeanInstantiationContributor buildAotContributor(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName) {
+	public BeanInstantiationContribution contribute(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName) {
 		InjectionMetadata metadata = findInjectionMetadata(beanName, beanType, beanDefinition);
 		Collection<InjectedElement> injectedElements = metadata.getInjectedElements();
 		return (!ObjectUtils.isEmpty(injectedElements)
-				? new AutowiredAnnotationBeanInstantiationContributor(injectedElements)
-				: BeanInstantiationContributor.NO_OP);
+				? new AutowiredAnnotationBeanInstantiationContribution(injectedElements)
+				: null);
 	}
 
 	private InjectionMetadata findInjectionMetadata(String beanName, Class<?> beanType, RootBeanDefinition beanDefinition) {
@@ -821,19 +821,19 @@ public class AutowiredAnnotationBeanPostProcessor implements SmartInstantiationA
 		}
 	}
 
-	private static final class AutowiredAnnotationBeanInstantiationContributor implements BeanInstantiationContributor {
+	private static final class AutowiredAnnotationBeanInstantiationContribution implements BeanInstantiationContribution {
 
 		private final Collection<InjectedElement> injectedElements;
 
 		private final InjectionGenerator generator;
 
-		AutowiredAnnotationBeanInstantiationContributor(Collection<InjectedElement> injectedElements) {
+		AutowiredAnnotationBeanInstantiationContribution(Collection<InjectedElement> injectedElements) {
 			this.injectedElements = injectedElements;
 			this.generator = new InjectionGenerator();
 		}
 
 		@Override
-		public void contribute(CodeContribution contribution) {
+		public void applyTo(CodeContribution contribution) {
 			this.injectedElements.forEach(element -> {
 				boolean isRequired = isRequired(element);
 				Member member = element.getMember();

spring-beans/src/main/java/org/springframework/beans/factory/generator/AotContributingBeanPostProcessor.java

@@ -18,6 +18,7 @@ package org.springframework.beans.factory.generator;
 
 import org.springframework.beans.factory.config.BeanPostProcessor;
 import org.springframework.beans.factory.support.RootBeanDefinition;
+import org.springframework.lang.Nullable;
 
 /**
  * Specialization of {@link BeanPostProcessor} that contributes to bean
@@ -35,12 +36,14 @@ import org.springframework.beans.factory.support.RootBeanDefinition;
 public interface AotContributingBeanPostProcessor extends BeanPostProcessor {
 
 	/**
-	 * Build a {@link BeanInstantiationContributor} for the given bean definition.
+	 * Contribute a {@link BeanInstantiationContribution} for the given bean definition,
+	 * if applicable.
 	 * @param beanDefinition the merged bean definition for the bean
 	 * @param beanType the inferred type of the bean
 	 * @param beanName the name of the bean
-	 * @return the contributor to use
+	 * @return the contribution to use or {@code null} if the bean should not be processed
 	 */
-	BeanInstantiationContributor buildAotContributor(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName);
+	@Nullable
+	BeanInstantiationContribution contribute(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName);
 
 }

spring-beans/src/main/java/org/springframework/beans/factory/generator/BeanInstantiationContribution.java

@@ -19,24 +19,18 @@ package org.springframework.beans.factory.generator;
 import org.springframework.aot.generator.CodeContribution;
 
 /**
- * Contributor to the code that instantiates a bean following ahead of time
+ * A contribution to the instantiation of a bean following ahead of time
  * processing.
  *
  * @author Stephane Nicoll
  * @since 6.0
  */
 @FunctionalInterface
-public interface BeanInstantiationContributor {
+public interface BeanInstantiationContribution {
 
 	/**
-	 * A {@link BeanInstantiationContributor} that does not contribute anything
-	 * to the {@link CodeContribution}.
-	 */
-	BeanInstantiationContributor NO_OP = contribution -> { };
-
-	/**
-	 * Contribute to the specified {@link CodeContribution}.
-	 * <p>Implementation of this interface can assume the following variables
+	 * Contribute bean instantiation to the specified {@link CodeContribution}.
+	 * <p>Implementations of this interface can assume the following variables
 	 * to be accessible:
 	 * <ul>
 	 * <li>{@code beanFactory}: the general {@code DefaultListableBeanFactory}</li>
@@ -45,6 +39,6 @@ public interface BeanInstantiationContributor {
 	 * </ul>
 	 * @param contribution the {@link CodeContribution} to use
 	 */
-	void contribute(CodeContribution contribution);
+	void applyTo(CodeContribution contribution);
 
 }

spring-beans/src/main/java/org/springframework/beans/factory/generator/DefaultBeanInstantiationGenerator.java

@@ -36,25 +36,25 @@ import org.springframework.util.ClassUtils;
  * Write the necessary statements to instantiate a bean.
  *
  * @author Stephane Nicoll
- * @see BeanInstantiationContributor
+ * @see BeanInstantiationContribution
  */
 class DefaultBeanInstantiationGenerator {
 
 	private final Executable instanceCreator;
 
-	private final List<BeanInstantiationContributor> contributors;
+	private final List<BeanInstantiationContribution> contributions;
 
 	private final InjectionGenerator injectionGenerator;
 
 	private final Options beanInstanceOptions;
 
 
-	DefaultBeanInstantiationGenerator(Executable instanceCreator, List<BeanInstantiationContributor> contributors) {
+	DefaultBeanInstantiationGenerator(Executable instanceCreator, List<BeanInstantiationContribution> contributions) {
 		this.instanceCreator = instanceCreator;
-		this.contributors = List.copyOf(contributors);
+		this.contributions = List.copyOf(contributions);
 		this.injectionGenerator = new InjectionGenerator();
 		this.beanInstanceOptions = Options.defaults().useReflection(member -> false)
-				.assignReturnType(member -> !this.contributors.isEmpty()).build();
+				.assignReturnType(member -> !this.contributions.isEmpty()).build();
 	}
 
 	/**
@@ -78,7 +78,7 @@ class DefaultBeanInstantiationGenerator {
 	private void writeBeanInstantiation(CodeContribution contribution, Constructor<?> constructor) {
 		Class<?> declaringType = ClassUtils.getUserClass(constructor.getDeclaringClass());
 		boolean innerClass = isInnerClass(declaringType);
-		boolean multiStatements = !this.contributors.isEmpty();
+		boolean multiStatements = !this.contributions.isEmpty();
 		int minArgs = isInnerClass(declaringType) ? 2 : 1;
 		CodeBlock.Builder code = CodeBlock.builder();
 		// Shortcut for common case
@@ -110,8 +110,8 @@ class DefaultBeanInstantiationGenerator {
 		contribution.statements().addStatement(code.build());
 
 		if (multiStatements) {
-			for (BeanInstantiationContributor contributor : this.contributors) {
-				contributor.contribute(contribution);
+			for (BeanInstantiationContribution contributor : this.contributions) {
+				contributor.applyTo(contribution);
 			}
 			contribution.statements().addStatement("return bean")
 					.add(codeBlock -> codeBlock.unindent().add("}"));
@@ -127,7 +127,7 @@ class DefaultBeanInstantiationGenerator {
 		contribution.runtimeHints().reflection().registerMethod(method,
 				hint -> hint.withMode(ExecutableMode.INTROSPECT));
 		List<Class<?>> parameterTypes = new ArrayList<>(Arrays.asList(method.getParameterTypes()));
-		boolean multiStatements = !this.contributors.isEmpty();
+		boolean multiStatements = !this.contributions.isEmpty();
 		Class<?> declaringType = method.getDeclaringClass();
 		CodeBlock.Builder code = CodeBlock.builder();
 		// Shortcut for common case
@@ -148,8 +148,8 @@ class DefaultBeanInstantiationGenerator {
 		code.add(this.injectionGenerator.writeInstantiation(method));
 		contribution.statements().addStatement(code.build());
 		if (multiStatements) {
-			for (BeanInstantiationContributor contributor : this.contributors) {
-				contributor.contribute(contribution);
+			for (BeanInstantiationContribution contributor : this.contributions) {
+				contributor.applyTo(contribution);
 			}
 			contribution.statements().addStatement("return bean")
 					.add(codeBlock -> codeBlock.unindent().add("}"));

spring-beans/src/test/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanInstantiationContributorTests.java

@@ -24,11 +24,12 @@ import org.springframework.aot.hint.ExecutableMode;
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.aot.hint.TypeReference;
 import org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessorTests.ResourceInjectionBean;
-import org.springframework.beans.factory.generator.BeanInstantiationContributor;
+import org.springframework.beans.factory.generator.BeanInstantiationContribution;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.beans.testfixture.beans.TestBean;
 import org.springframework.core.env.Environment;
 import org.springframework.javapoet.support.CodeSnippet;
+import org.springframework.lang.Nullable;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -37,10 +38,10 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Stephane Nicoll
  */
-class AutowiredAnnotationBeanInstantiationContributorTests {
+class AutowiredAnnotationBeanInstantiationContributionTests {
 
 	@Test
-	void buildAotContributorWithPackageProtectedFieldInjection() {
+	void contributeWithPackageProtectedFieldInjection() {
 		CodeContribution contribution = contribute(PackageProtectedFieldInjectionSample.class);
 		assertThat(CodeSnippet.process(contribution.statements().toCodeBlock())).isEqualTo("""
 				instanceContext.field("environment", Environment.class)
@@ -58,12 +59,12 @@ class AutowiredAnnotationBeanInstantiationContributorTests {
 	}
 
 	@Test
-	void buildAotContributorWithPrivateFieldInjection() {
+	void contributeWithPrivateFieldInjection() {
 		CodeContribution contribution = contribute(PrivateFieldInjectionSample.class);
 		assertThat(CodeSnippet.process(contribution.statements().toCodeBlock())).isEqualTo("""
 				instanceContext.field("environment", Environment.class)
 						.invoke(beanFactory, (attributes) -> {
-							Field environmentField = ReflectionUtils.findField(AutowiredAnnotationBeanInstantiationContributorTests.PrivateFieldInjectionSample.class, "environment", Environment.class);
+							Field environmentField = ReflectionUtils.findField(AutowiredAnnotationBeanInstantiationContributionTests.PrivateFieldInjectionSample.class, "environment", Environment.class);
 							ReflectionUtils.makeAccessible(environmentField);
 							ReflectionUtils.setField(environmentField, bean, attributes.get(0));
 						})""");
@@ -79,7 +80,7 @@ class AutowiredAnnotationBeanInstantiationContributorTests {
 	}
 
 	@Test
-	void buildAotContributorWithPublicMethodInjection() {
+	void contributeWithPublicMethodInjection() {
 		CodeContribution contribution = contribute(PublicMethodInjectionSample.class);
 		assertThat(CodeSnippet.process(contribution.statements().toCodeBlock())).isEqualTo("""
 				instanceContext.method("setTestBean", TestBean.class)
@@ -95,7 +96,7 @@ class AutowiredAnnotationBeanInstantiationContributorTests {
 	}
 
 	@Test
-	void buildAotContributorWithInjectionPoints() {
+	void contributeWithInjectionPoints() {
 		CodeContribution contribution = contribute(ResourceInjectionBean.class);
 		assertThat(CodeSnippet.process(contribution.statements().toCodeBlock())).isEqualTo("""
 				instanceContext.field("testBean", TestBean.class)
@@ -116,23 +117,24 @@ class AutowiredAnnotationBeanInstantiationContributorTests {
 	}
 
 	@Test
-	void buildAotContributorWithoutInjectionPoints() {
-		BeanInstantiationContributor contributor = createAotContributor(String.class);
-		assertThat(contributor).isNotNull().isSameAs(BeanInstantiationContributor.NO_OP);
+	void contributeWithoutInjectionPoints() {
+		BeanInstantiationContribution contributor = createContribution(String.class);
+		assertThat(contributor).isNull();
 	}
 
 	private DefaultCodeContribution contribute(Class<?> type) {
-		BeanInstantiationContributor contributor = createAotContributor(type);
+		BeanInstantiationContribution contributor = createContribution(type);
 		assertThat(contributor).isNotNull();
 		DefaultCodeContribution contribution = new DefaultCodeContribution(new RuntimeHints());
-		contributor.contribute(contribution);
+		contributor.applyTo(contribution);
 		return contribution;
 	}
 
-	private BeanInstantiationContributor createAotContributor(Class<?> type) {
+	@Nullable
+	private BeanInstantiationContribution createContribution(Class<?> type) {
 		AutowiredAnnotationBeanPostProcessor bpp = new AutowiredAnnotationBeanPostProcessor();
 		RootBeanDefinition beanDefinition = new RootBeanDefinition(type);
-		return bpp.buildAotContributor(beanDefinition, type, "test");
+		return bpp.contribute(beanDefinition, type, "test");
 	}
 
 

spring-beans/src/test/java/org/springframework/beans/factory/generator/DefaultBeanInstantiationGeneratorTests.java

@@ -106,10 +106,10 @@ class DefaultBeanInstantiationGeneratorTests {
 	}
 
 	@Test
-	void generateUsingNoArgConstructorAndContributorsDoesNotUseMethodReference() {
+	void generateUsingNoArgConstructorAndContributionsDoesNotUseMethodReference() {
 		CodeContribution contribution = generate(SimpleConfiguration.class.getDeclaredConstructors()[0],
 				contrib -> contrib.statements().add(CodeBlock.of("// hello\n")),
-				BeanInstantiationContributor.NO_OP);
+				contrib -> {});
 		assertThat(code(contribution)).isEqualTo("""
 				(instanceContext) -> {
 					SimpleConfiguration bean = new SimpleConfiguration();
@@ -119,7 +119,7 @@ class DefaultBeanInstantiationGeneratorTests {
 	}
 
 	@Test
-	void generateUsingContributorsRegisterHints() {
+	void generateUsingContributionsRegisterHints() {
 		CodeContribution contribution = generate(SimpleConfiguration.class.getDeclaredConstructors()[0],
 				contrib -> {
 					contrib.statements().add(CodeBlock.of("// hello\n"));
@@ -170,7 +170,7 @@ class DefaultBeanInstantiationGeneratorTests {
 	}
 
 	@Test
-	void generateUsingMethodAndContributors() {
+	void generateUsingMethodAndContributions() {
 		CodeContribution contribution = generate(method(SimpleConfiguration.class, "stringBean"),
 				contrib -> {
 					contrib.statements().add(CodeBlock.of("// hello\n"));
@@ -240,9 +240,9 @@ class DefaultBeanInstantiationGeneratorTests {
 	}
 
 	private CodeContribution generate(Executable executable,
-			BeanInstantiationContributor... beanInstantiationContributors) {
+			BeanInstantiationContribution... beanInstantiationContributions) {
 		DefaultBeanInstantiationGenerator generator = new DefaultBeanInstantiationGenerator(executable,
-				Arrays.asList(beanInstantiationContributors));
+				Arrays.asList(beanInstantiationContributions));
 		return generator.generateBeanInstantiation(new RuntimeHints());
 	}