#1599 - Properly contextualize MapSuppressingUnwrappingSerializer.

According to FasterXML/jackson-databind#3272, we have to explicitly contextualize the delegate serializer we use for non-Map content in EntityModel.

src/main/java/org/springframework/hateoas/EntityModel.java

@@ -22,6 +22,7 @@ import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.Map;
 
+import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
@@ -29,9 +30,12 @@ import com.fasterxml.jackson.annotation.JsonAnyGetter;
 import com.fasterxml.jackson.annotation.JsonAnySetter;
 import com.fasterxml.jackson.annotation.JsonUnwrapped;
 import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.databind.BeanProperty;
+import com.fasterxml.jackson.databind.JsonMappingException;
 import com.fasterxml.jackson.databind.JsonSerializer;
 import com.fasterxml.jackson.databind.SerializerProvider;
 import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+import com.fasterxml.jackson.databind.ser.ContextualSerializer;
 import com.fasterxml.jackson.databind.ser.std.JsonValueSerializer;
 import com.fasterxml.jackson.databind.ser.std.StdSerializer;
 import com.fasterxml.jackson.databind.util.NameTransformer;
@@ -197,10 +201,23 @@ public class EntityModel<T> extends RepresentationModel<EntityModel<T>> {
 		return result;
 	}
 
-	private static class MapSuppressingUnwrappingSerializer extends StdSerializer<Object> {
+	private static class MapSuppressingUnwrappingSerializer extends StdSerializer<Object>
+			implements ContextualSerializer {
 
+		private static final long serialVersionUID = -8367255762553946324L;
+
+		private final @Nullable BeanProperty property;
+
+		@SuppressWarnings("unused")
 		public MapSuppressingUnwrappingSerializer() {
+			this(null);
+		}
+
+		private MapSuppressingUnwrappingSerializer(@Nullable BeanProperty property) {
+
 			super(Object.class);
+
+			this.property = property;
 		}
 
 		/*
@@ -208,7 +225,9 @@ public class EntityModel<T> extends RepresentationModel<EntityModel<T>> {
 		 * @see com.fasterxml.jackson.databind.ser.std.StdSerializer#serialize(java.lang.Object, com.fasterxml.jackson.core.JsonGenerator, com.fasterxml.jackson.databind.SerializerProvider)
 		 */
 		@Override
-		public void serialize(Object value, JsonGenerator gen, SerializerProvider provider) throws IOException {
+		@SuppressWarnings({ "null", "unchecked" })
+		public void serialize(@Nullable Object value, @Nullable JsonGenerator gen, @NonNull SerializerProvider provider)
+				throws IOException {
 
 			if (value == null || Map.class.isInstance(value)) {
 				return;
@@ -221,11 +240,25 @@ public class EntityModel<T> extends RepresentationModel<EntityModel<T>> {
 						"@JsonValue rendered classes can not be directly nested in EntityModel as they do not produce a document key!");
 			}
 
+			if (ContextualSerializer.class.isInstance(serializer)) {
+				serializer = (JsonSerializer<Object>) ((ContextualSerializer) serializer).createContextual(provider, property);
+			}
+
 			serializer //
 					.unwrappingSerializer(NameTransformer.NOP) //
 					.serialize(value, gen, provider);
 		}
 
+		/*
+		 * (non-Javadoc)
+		 * @see com.fasterxml.jackson.databind.ser.ContextualSerializer#createContextual(com.fasterxml.jackson.databind.SerializerProvider, com.fasterxml.jackson.databind.BeanProperty)
+		 */
+		@Override
+		public JsonSerializer<?> createContextual(@Nullable SerializerProvider prov, @Nullable BeanProperty property)
+				throws JsonMappingException {
+			return new MapSuppressingUnwrappingSerializer(property);
+		}
+
 		/*
 		 * (non-Javadoc)
 		 * @see com.fasterxml.jackson.databind.JsonSerializer#isUnwrappingSerializer()

src/test/java/org/springframework/hateoas/EntityModelUnitTest.java

@@ -21,7 +21,9 @@ import java.util.Collections;
 
 import org.junit.jupiter.api.Test;
 
+import com.fasterxml.jackson.annotation.JsonIdentityInfo;
 import com.fasterxml.jackson.annotation.JsonValue;
+import com.fasterxml.jackson.annotation.ObjectIdGenerators;
 import com.fasterxml.jackson.databind.JsonMappingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
@@ -88,9 +90,23 @@ class EntityModelUnitTest {
 				.withMessageContaining("@JsonValue");
 	}
 
+	@Test // #1371
+	void rendersTypeIdentifiersCorrectly() throws Exception {
+
+		EntityModel<?> model = EntityModel.of(new TypeWithId());
+
+		assertThatNoException()
+				.isThrownBy(() -> new ObjectMapper().writeValueAsString(model));
+	}
+
 	// #1371
 
 	static class ValueType {
 		@JsonValue String type;
 	}
+
+	@JsonIdentityInfo(generator = ObjectIdGenerators.UUIDGenerator.class, property = "@jsonObjectId")
+	static class TypeWithId {
+
+	}
 }