Polish "Support unwrapping in ValidatorAdapter"

See gh-37119

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/validation/ValidatorAdapter.java

@@ -157,14 +157,10 @@ public class ValidatorAdapter implements SmartValidator, ApplicationContextAware
 	@Override
 	@SuppressWarnings("unchecked")
 	public <T> T unwrap(Class<T> type) {
-		if (type.isAssignableFrom(this.target.getClass())) {
-			if (this.target instanceof SpringValidatorAdapter adapter) {
-				return adapter.unwrap(type);
-			}
+		if (type.isInstance(this.target)) {
 			return (T) this.target;
 		}
-
-		throw new IllegalArgumentException("Cannot unwrap " + this.target + " to " + type.getName());
+		return this.target.unwrap(type);
 	}
 
 }

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/validation/ValidatorAdapterTests.java

@@ -21,7 +21,6 @@ import java.util.HashMap;
 import jakarta.validation.Validator;
 import jakarta.validation.constraints.Min;
 import org.hibernate.validator.HibernateValidator;
-import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.test.context.FilteredClassLoader;
@@ -30,10 +29,13 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.io.ClassPathResource;
+import org.springframework.validation.Errors;
 import org.springframework.validation.MapBindingResult;
+import org.springframework.validation.SmartValidator;
 import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatRuntimeException;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.BDDMockito.then;
 import static org.mockito.Mockito.mock;
@@ -95,11 +97,26 @@ class ValidatorAdapterTests {
 	}
 
 	@Test
-	void unwrapValidatorInstanceOfJakartaTypeAndExceptionThrownWhenTypeNotSupported() {
+	void unwrapToJakartaValidatorShouldReturnJakartaValidator() {
 		this.contextRunner.withUserConfiguration(LocalValidatorFactoryBeanConfig.class).run((context) -> {
 			ValidatorAdapter wrapper = context.getBean(ValidatorAdapter.class);
 			assertThat(wrapper.unwrap(Validator.class)).isInstanceOf(Validator.class);
-			Assertions.assertThrows(IllegalArgumentException.class, () -> wrapper.unwrap(HibernateValidator.class));
+		});
+	}
+
+	@Test
+	void whenJakartaValidatorIsWrappedMultipleTimesUnwrapToJakartaValidatorShouldReturnJakartaValidator() {
+		this.contextRunner.withUserConfiguration(DoubleWrappedConfig.class).run((context) -> {
+			ValidatorAdapter wrapper = context.getBean(ValidatorAdapter.class);
+			assertThat(wrapper.unwrap(Validator.class)).isInstanceOf(Validator.class);
+		});
+	}
+
+	@Test
+	void unwrapToUnsupportedTypeShouldThrow() {
+		this.contextRunner.withUserConfiguration(LocalValidatorFactoryBeanConfig.class).run((context) -> {
+			ValidatorAdapter wrapper = context.getBean(ValidatorAdapter.class);
+			assertThatRuntimeException().isThrownBy(() -> wrapper.unwrap(HibernateValidator.class));
 		});
 	}
 
@@ -118,6 +135,55 @@ class ValidatorAdapterTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class DoubleWrappedConfig {
+
+		@Bean
+		LocalValidatorFactoryBean validator() {
+			return new LocalValidatorFactoryBean();
+		}
+
+		@Bean
+		ValidatorAdapter wrapper(LocalValidatorFactoryBean validator) {
+			return new ValidatorAdapter(new Wrapper(validator), true);
+		}
+
+		static class Wrapper implements SmartValidator {
+
+			private final SmartValidator delegate;
+
+			Wrapper(SmartValidator delegate) {
+				this.delegate = delegate;
+			}
+
+			@Override
+			public boolean supports(Class<?> clazz) {
+				return this.delegate.supports(clazz);
+			}
+
+			@Override
+			public void validate(Object target, Errors errors) {
+				this.delegate.validate(target, errors);
+			}
+
+			@Override
+			public void validate(Object target, Errors errors, Object... validationHints) {
+				this.delegate.validate(target, errors, validationHints);
+			}
+
+			@Override
+			@SuppressWarnings("unchecked")
+			public <T> T unwrap(Class<T> type) {
+				if (type.isInstance(this.delegate)) {
+					return (T) this.delegate;
+				}
+				return this.delegate.unwrap(type);
+			}
+
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class NonManagedBeanConfig {