Simplify the generation of inner bean definitions

See gh-28047

Author: snicoll

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

@@ -24,7 +24,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.function.BiConsumer;
 import java.util.function.Function;
 import java.util.function.Supplier;
 import java.util.stream.Collectors;
@@ -52,23 +51,23 @@ public final class BeanParameterGenerator {
 
 	private final ResolvableTypeGenerator typeGenerator = new ResolvableTypeGenerator();
 
-	private final BiConsumer<BeanDefinition, Builder> innerBeanDefinitionGenerator;
+	private final Function<BeanDefinition, CodeBlock> innerBeanDefinitionGenerator;
 
 
 	/**
 	 * Create an instance with the callback to use to generate an inner bean
 	 * definition.
 	 * @param innerBeanDefinitionGenerator the inner bean definition generator
 	 */
-	public BeanParameterGenerator(BiConsumer<BeanDefinition, Builder> innerBeanDefinitionGenerator) {
+	public BeanParameterGenerator(Function<BeanDefinition, CodeBlock> innerBeanDefinitionGenerator) {
 		this.innerBeanDefinitionGenerator = innerBeanDefinitionGenerator;
 	}
 
 	/**
 	 * Create an instance with no support for inner bean definitions.
 	 */
 	public BeanParameterGenerator() {
-		this((beanDefinition, builder) -> {
+		this(beanDefinition -> {
 			throw new IllegalStateException("Inner bean definition is not supported by this instance");
 		});
 	}
@@ -174,8 +173,8 @@ else if (value instanceof Class) {
 		else if (value instanceof ResolvableType) {
 			code.add(this.typeGenerator.generateTypeFor((ResolvableType) value));
 		}
-		else if (value instanceof BeanDefinition) {
-			this.innerBeanDefinitionGenerator.accept((BeanDefinition) value, code);
+		else if (value instanceof BeanDefinition bd) {
+			code.add(this.innerBeanDefinitionGenerator.apply(bd));
 		}
 		else if (value instanceof BeanReference) {
 			code.add("new $T($S)", RuntimeBeanReference.class, ((BeanReference) value).getBeanName());

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

@@ -40,6 +40,7 @@
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.io.ResourceLoader;
+import org.springframework.javapoet.CodeBlock;
 import org.springframework.javapoet.support.CodeSnippet;
 import org.springframework.lang.Nullable;
 import org.springframework.util.ReflectionUtils;
@@ -221,7 +222,7 @@ void generateBeanReference() {
 	@Test
 	void generateBeanDefinitionCallsConsumer() {
 		BeanParameterGenerator customGenerator = new BeanParameterGenerator(
-				((beanDefinition, builder) -> builder.add("test")));
+				beanDefinition -> CodeBlock.of("test"));
 		assertThat(CodeSnippet.process(customGenerator.generateParameterValue(
 				new RootBeanDefinition()))).isEqualTo("test");
 	}