Add support of declarative use of reflection

This commit adds a `@Reflective` annotation that can be used to declare
that the annotated element requires reflection at runtime. By default,
the annotated element is exposed but this can be customized by
specifying a dedicated `ReflectiveProcessor`.

Closes gh-28469

spring-core/src/test/java/org/springframework/aot/hint/annotation/SimpleReflectiveProcessorTests.java

@@ -0,0 +1,115 @@
+/*
+ * 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.annotation;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.aot.hint.ExecutableMode;
+import org.springframework.aot.hint.ReflectionHints;
+import org.springframework.aot.hint.TypeReference;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link SimpleReflectiveProcessor}.
+ *
+ * @author Stephane Nicoll
+ */
+class SimpleReflectiveProcessorTests {
+
+	private final SimpleReflectiveProcessor processor = new SimpleReflectiveProcessor();
+
+	private final ReflectionHints hints = new ReflectionHints();
+
+	@Test
+	void registerReflectiveHintsForClass() {
+		processor.registerReflectionHints(hints, SampleBean.class);
+		assertThat(hints.typeHints()).singleElement().satisfies(typeHint -> {
+			assertThat(typeHint.getType()).isEqualTo(TypeReference.of(SampleBean.class));
+			assertThat(typeHint.getMemberCategories()).isEmpty();
+			assertThat(typeHint.constructors()).isEmpty();
+			assertThat(typeHint.fields()).isEmpty();
+			assertThat(typeHint.methods()).isEmpty();
+		});
+	}
+
+	@Test
+	void registerReflectiveHintsForConstructor() {
+		Constructor<?> constructor = SampleBean.class.getDeclaredConstructors()[0];
+		processor.registerReflectionHints(hints, constructor);
+		assertThat(hints.typeHints()).singleElement().satisfies(typeHint -> {
+			assertThat(typeHint.getType()).isEqualTo(TypeReference.of(SampleBean.class));
+			assertThat(typeHint.getMemberCategories()).isEmpty();
+			assertThat(typeHint.constructors()).singleElement().satisfies(constructorHint -> {
+				assertThat(constructorHint.getName()).isEqualTo("<init>");
+				assertThat(constructorHint.getModes()).containsExactly(ExecutableMode.INVOKE);
+				assertThat(constructorHint.getParameterTypes()).containsExactly(TypeReference.of(String.class));
+			});
+			assertThat(typeHint.fields()).isEmpty();
+			assertThat(typeHint.methods()).isEmpty();
+		});
+	}
+
+	@Test
+	void registerReflectiveHintsForField() throws NoSuchFieldException {
+		Field field = SampleBean.class.getDeclaredField("name");
+		processor.registerReflectionHints(hints, field);
+		assertThat(hints.typeHints()).singleElement().satisfies(typeHint -> {
+			assertThat(typeHint.getType()).isEqualTo(TypeReference.of(SampleBean.class));
+			assertThat(typeHint.getMemberCategories()).isEmpty();
+			assertThat(typeHint.constructors()).isEmpty();
+			assertThat(typeHint.fields()).singleElement().satisfies(fieldHint ->
+					assertThat(fieldHint.getName()).isEqualTo("name"));
+			assertThat(typeHint.methods()).isEmpty();
+		});
+	}
+
+	@Test
+	void registerReflectiveHintsForMethod() throws NoSuchMethodException {
+		Method method = SampleBean.class.getDeclaredMethod("setName", String.class);
+		processor.registerReflectionHints(hints, method);
+		assertThat(hints.typeHints()).singleElement().satisfies(typeHint -> {
+			assertThat(typeHint.getType()).isEqualTo(TypeReference.of(SampleBean.class));
+			assertThat(typeHint.getMemberCategories()).isEmpty();
+			assertThat(typeHint.constructors()).isEmpty();
+			assertThat(typeHint.fields()).isEmpty();
+			assertThat(typeHint.methods()).singleElement().satisfies(methodHint -> {
+				assertThat(methodHint.getName()).isEqualTo("setName");
+				assertThat(methodHint.getModes()).containsExactly(ExecutableMode.INVOKE);
+				assertThat(methodHint.getParameterTypes()).containsExactly(TypeReference.of(String.class));
+			});
+		});
+	}
+
+	static class SampleBean {
+
+		private String name;
+
+		SampleBean(String name) {
+			this.name = name;
+		}
+
+		public void setName(String name) {
+			this.name = name;
+		}
+	}
+
+}