#1983 - Additional reflection hints for custom Jackson serializer in …

…EntityModel.

We now register reflection hints for all types contained in EntityModel, so that MapSuppressingUnwrappingSerializer's default constructor can be called from Jackson.

Original ticket: #1981
Related ticket: spring-projects/spring-boot#36057

src/main/java/org/springframework/hateoas/aot/RepresentationModelRuntimeHints.java

@@ -15,10 +15,11 @@
  */
 package org.springframework.hateoas.aot;
 
+import java.util.Arrays;
 import java.util.List;
+import java.util.stream.Stream;
 
 import org.springframework.aot.hint.MemberCategory;
-import org.springframework.aot.hint.ReflectionHints;
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.aot.hint.RuntimeHintsRegistrar;
 import org.springframework.hateoas.CollectionModel;
@@ -34,7 +35,7 @@
 class RepresentationModelRuntimeHints implements RuntimeHintsRegistrar {
 
 	private static final List<Class<?>> REPRESENTATION_MODELS = List.of(RepresentationModel.class, //
-			EntityModel.class, //
+			// EntityModel.class, // treated specially below
 			CollectionModel.class, //
 			PagedModel.class,
 			PagedModel.PageMetadata.class);
@@ -46,9 +47,12 @@ class RepresentationModelRuntimeHints implements RuntimeHintsRegistrar {
 	@Override
 	public void registerHints(RuntimeHints hints, ClassLoader classLoader) {
 
-		ReflectionHints reflection = hints.reflection();
+		var reflection = hints.reflection();
+		var entityModelAndNested = Arrays.stream(EntityModel.class.getNestMembers());
 
-		REPRESENTATION_MODELS.forEach(it -> reflection.registerType(it, //
-				MemberCategory.INVOKE_DECLARED_CONSTRUCTORS, MemberCategory.INVOKE_DECLARED_METHODS));
+		Stream.concat(REPRESENTATION_MODELS.stream(), entityModelAndNested).forEach(it -> { //
+			reflection.registerType(it, //
+					MemberCategory.INVOKE_DECLARED_CONSTRUCTORS, MemberCategory.INVOKE_DECLARED_METHODS);
+		});
 	}
 }

src/test/java/org/springframework/hateoas/aot/RepresentationModelRuntimeHintsUnitTests.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 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.hateoas.aot;
+
+import static org.assertj.core.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.aot.hint.TypeHint;
+import org.springframework.aot.hint.TypeReference;
+
+/**
+ * Unit tests for {@link RepresentationModelRuntimeHints}.
+ *
+ * @author Oliver Drotbohm
+ */
+class RepresentationModelRuntimeHintsUnitTests {
+
+	@Test // GH-1981
+	void registersHintsForMapSuppressingUnwrappingSerializer() {
+
+		var registrar = new RepresentationModelRuntimeHints();
+		var hints = new RuntimeHints();
+
+		registrar.registerHints(hints, getClass().getClassLoader());
+
+		assertThat(hints.reflection().typeHints())
+				.extracting(TypeHint::getType)
+				.extracting(TypeReference::getSimpleName)
+				.contains("MapSuppressingUnwrappingSerializer");
+	}
+}