Infer hints for custom constraint validators

This commit introduces a BeanValidationBeanRegistrationAotProcessor
which adds reflection hints for custom ConstraintValidator discovered
on beans constructors, methods and properties.

Closes gh-29823

spring-context/src/test/java/org/springframework/validation/beanvalidation/BeanValidationBeanRegistrationAotProcessorTests.java

@@ -0,0 +1,168 @@
+/*
+ * Copyright 2002-2023 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.validation.beanvalidation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Repeatable;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import jakarta.validation.Constraint;
+import jakarta.validation.ConstraintValidator;
+import jakarta.validation.ConstraintValidatorContext;
+import jakarta.validation.Payload;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.aot.generate.GenerationContext;
+import org.springframework.aot.hint.MemberCategory;
+import org.springframework.aot.hint.predicate.RuntimeHintsPredicates;
+import org.springframework.aot.test.generate.TestGenerationContext;
+import org.springframework.beans.factory.aot.BeanRegistrationAotContribution;
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
+import org.springframework.beans.factory.support.RegisteredBean;
+import org.springframework.beans.factory.support.RootBeanDefinition;
+import org.springframework.lang.Nullable;
+
+import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
+import static java.lang.annotation.ElementType.CONSTRUCTOR;
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE_USE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for {@link BeanValidationBeanRegistrationAotProcessor}.
+ *
+ * @author Sebastien Deleuze
+ */
+class BeanValidationBeanRegistrationAotProcessorTests {
+
+	private final BeanValidationBeanRegistrationAotProcessor processor = new BeanValidationBeanRegistrationAotProcessor();
+
+	private final GenerationContext generationContext = new TestGenerationContext();
+
+	@Test
+	void shouldSkipNonAnnotatedType() {
+		process(EmptyClass.class);
+		assertThat(this.generationContext.getRuntimeHints().reflection().typeHints()).isEmpty();
+	}
+
+	@Test
+	void shouldProcessMethodParameterLevelConstraint() {
+		process(MethodParameterLevelConstraint.class);
+		assertThat(RuntimeHintsPredicates.reflection().onType(ExistsValidator.class)
+				.withMemberCategory(MemberCategory.INVOKE_DECLARED_CONSTRUCTORS)).accepts(this.generationContext.getRuntimeHints());
+	}
+
+	@Test
+	void shouldProcessConstructorParameterLevelConstraint() {
+		process(ConstructorParameterLevelConstraint.class);
+		assertThat(RuntimeHintsPredicates.reflection().onType(ExistsValidator.class)
+				.withMemberCategory(MemberCategory.INVOKE_DECLARED_CONSTRUCTORS)).accepts(this.generationContext.getRuntimeHints());
+	}
+
+	@Test
+	void shouldProcessPropertyLevelConstraint() {
+		process(PropertyLevelConstraint.class);
+		assertThat(RuntimeHintsPredicates.reflection().onType(ExistsValidator.class)
+				.withMemberCategory(MemberCategory.INVOKE_DECLARED_CONSTRUCTORS)).accepts(this.generationContext.getRuntimeHints());
+	}
+
+	private void process(Class<?> beanClass) {
+		BeanRegistrationAotContribution contribution = createContribution(beanClass);
+		if (contribution != null) {
+			contribution.applyTo(this.generationContext, mock());
+		}
+	}
+
+	@Nullable
+	private BeanRegistrationAotContribution createContribution(Class<?> beanClass) {
+		DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
+		beanFactory.registerBeanDefinition(beanClass.getName(), new RootBeanDefinition(beanClass));
+		return this.processor.processAheadOfTime(RegisteredBean.of(beanFactory, beanClass.getName()));
+	}
+
+	private static class EmptyClass { }
+
+	@Constraint(validatedBy = { ExistsValidator.class })
+	@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
+	@Retention(RUNTIME)
+	@Repeatable(Exists.List.class)
+	private @interface Exists {
+
+		String message() default "Does not exists";
+
+		Class<?>[] groups() default { };
+
+		Class<? extends Payload>[] payload() default { };
+
+		@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
+		@Retention(RUNTIME)
+		@Documented
+		@interface List {
+			Exists[] value();
+		}
+	}
+
+	private static class ExistsValidator implements ConstraintValidator<Exists, String> {
+
+		@Override
+		public boolean isValid(String value, ConstraintValidatorContext constraintValidatorContext) {
+			return true;
+		}
+	}
+
+	private static class MethodParameterLevelConstraint {
+
+		public String hello(@Exists String name) {
+			return "Hello " + name;
+		}
+
+	}
+
+	private static class ConstructorParameterLevelConstraint {
+
+		private final String name;
+
+		public ConstructorParameterLevelConstraint(@Exists String name) {
+			this.name = name;
+		}
+
+		public String hello() {
+			return "Hello " + this.name;
+		}
+
+	}
+
+	private static class PropertyLevelConstraint {
+
+		@Exists
+		private String name;
+
+		public String getName() {
+			return name;
+		}
+
+		public void setName(String name) {
+			this.name = name;
+		}
+	}
+
+}