Add native hints for SpringFactoriesLoader file content

Add `SpringFactoriesLoaderRuntimeHintsRegistrar` which provides
native hints for `spring.factories` content.

Closes gh-27955

Co-authored-by: Phillip Webb <pwebb@vmware.com>

spring-core/src/test/java/org/springframework/core/io/support/SpringFactoriesLoaderRuntimeHintsRegistrarTests.java

@@ -0,0 +1,74 @@
+/*
+ * 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.core.io.support;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.aot.hint.MemberCategory;
+import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.aot.hint.RuntimeHintsRegistrar;
+import org.springframework.aot.hint.TypeHint;
+import org.springframework.aot.hint.TypeReference;
+import org.springframework.util.ClassUtils;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link SpringFactoriesLoaderRuntimeHintsRegistrar}.
+ *
+ * @author Phillip Webb
+ */
+class SpringFactoriesLoaderRuntimeHintsRegistrarTests {
+
+	private RuntimeHints hints;
+
+	@BeforeEach
+	void setup() {
+		this.hints = new RuntimeHints();
+		SpringFactoriesLoader.forResourceLocation("META-INF/spring/aot.factories")
+				.load(RuntimeHintsRegistrar.class).forEach(registrar -> registrar
+						.registerHints(this.hints, ClassUtils.getDefaultClassLoader()));
+	}
+
+	@Test
+	void resourceLocationHasHints() {
+		assertThat(this.hints.resources().resourcePatterns())
+				.anySatisfy(hint -> assertThat(hint.getIncludes())
+						.contains(SpringFactoriesLoader.FACTORIES_RESOURCE_LOCATION));
+	}
+
+	@Test
+	void factoryTypeHasHint() {
+		TypeReference type = TypeReference.of(DummyFactory.class);
+		assertThat(this.hints.reflection().getTypeHint(type))
+				.satisfies(this::expectedHints);
+	}
+
+	@Test
+	void factoryImplementationHasHint() {
+		TypeReference type = TypeReference.of(MyDummyFactory1.class);
+		assertThat(this.hints.reflection().getTypeHint(type))
+				.satisfies(this::expectedHints);
+	}
+
+	private void expectedHints(TypeHint hint) {
+		assertThat(hint.getMemberCategories())
+				.containsExactly(MemberCategory.INVOKE_DECLARED_CONSTRUCTORS);
+	}
+
+}