Add a common utility to register hints for an annotation

This commit adds a utility that takes care of registering the necessary
hints to make an annotation visible at runtime. The core framework may
create a JDK proxy if necessary, which requires specific handling.

Closes gh-28497

spring-core/src/test/java/org/springframework/aot/hint/support/RuntimeHintsUtilsTests.java

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2002-2022 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.aot.hint.support;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.aot.hint.MemberCategory;
+import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.aot.hint.TypeReference;
+import org.springframework.core.annotation.AliasFor;
+import org.springframework.core.annotation.MergedAnnotations;
+import org.springframework.core.annotation.SynthesizedAnnotation;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link RuntimeHintsUtils}.
+ *
+ * @author Stephane Nicoll
+ */
+class RuntimeHintsUtilsTests {
+
+	private final RuntimeHints hints = new RuntimeHints();
+
+	@Test
+	void registerAnnotation() {
+		RuntimeHintsUtils.registerAnnotation(this.hints, MergedAnnotations
+				.from(SampleInvokerClass.class).get(SampleInvoker.class));
+		assertThat(this.hints.reflection().getTypeHint(SampleInvoker.class)).satisfies(typeHint -> {
+			assertThat(typeHint.constructors()).isEmpty();
+			assertThat(typeHint.fields()).isEmpty();
+			assertThat(typeHint.methods()).isEmpty();
+			assertThat(typeHint.getMemberCategories()).containsOnly(MemberCategory.INVOKE_PUBLIC_METHODS);
+		});
+		assertThat(this.hints.proxies().jdkProxies()).isEmpty();
+	}
+
+	@Test
+	void registerAnnotationProxyRegistersJdkProxy() {
+		RuntimeHintsUtils.registerAnnotation(this.hints, MergedAnnotations
+				.from(RetryInvokerClass.class).get(RetryInvoker.class));
+		assertThat(this.hints.reflection().getTypeHint(RetryInvoker.class)).satisfies(typeHint -> {
+			assertThat(typeHint.constructors()).isEmpty();
+			assertThat(typeHint.fields()).isEmpty();
+			assertThat(typeHint.methods()).isEmpty();
+			assertThat(typeHint.getMemberCategories()).containsOnly(MemberCategory.INVOKE_PUBLIC_METHODS);
+		});
+		assertThat(this.hints.proxies().jdkProxies()).anySatisfy(jdkProxyHint ->
+				assertThat(jdkProxyHint.getProxiedInterfaces()).containsExactly(
+						TypeReference.of(RetryInvoker.class), TypeReference.of(SynthesizedAnnotation.class)));
+	}
+
+
+	@SampleInvoker
+	static class SampleInvokerClass {
+
+	}
+
+	@RetryInvoker
+	static class RetryInvokerClass {
+
+	}
+
+
+	@Target({ ElementType.TYPE, ElementType.ANNOTATION_TYPE })
+	@Retention(RetentionPolicy.RUNTIME)
+	@Documented
+	@interface SampleInvoker {
+
+		int retries() default 0;
+
+	}
+
+	@Target({ ElementType.TYPE })
+	@Retention(RetentionPolicy.RUNTIME)
+	@Documented
+	@SampleInvoker
+	@interface RetryInvoker {
+
+		@AliasFor(attribute = "retries", annotation = SampleInvoker.class)
+		int value() default 1;
+
+	}
+
+}

spring-core/src/test/java/org/springframework/core/annotation/CoreAnnotationsRuntimeHintsRegistrarTests.java

@@ -49,14 +49,14 @@ class CoreAnnotationsRuntimeHintsRegistrarTests {
 	void aliasForHasHints() {
 		assertThat(this.hints.reflection().getTypeHint(TypeReference.of(AliasFor.class)))
 				.satisfies(hint -> assertThat(hint.getMemberCategories())
-						.containsExactly(MemberCategory.INVOKE_DECLARED_METHODS));
+						.containsExactly(MemberCategory.INVOKE_PUBLIC_METHODS));
 	}
 
 	@Test
 	void orderAnnotationHasHints() {
 		assertThat(this.hints.reflection().getTypeHint(TypeReference.of(Order.class)))
 				.satisfies(hint -> assertThat(hint.getMemberCategories())
-						.containsExactly(MemberCategory.INVOKE_DECLARED_METHODS));
+						.containsExactly(MemberCategory.INVOKE_PUBLIC_METHODS));
 	}
 
 }