[spring-projects#1300] Fix jackson serialization test

Author: Patouche

src/main/java/org/springframework/hateoas/mediatype/JacksonHelper.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.hateoas.mediatype;
 
+import org.springframework.hateoas.AbstractCollectionModel;
 import org.springframework.hateoas.CollectionModel;
 import org.springframework.hateoas.EntityModel;
 
@@ -49,7 +50,7 @@ public static JavaType findRootType(JavaType contentType) {
 	public static boolean isResourcesOfResource(JavaType type) {
 
 		return
-			CollectionModel.class.isAssignableFrom(type.getRawClass())
+			AbstractCollectionModel.class.isAssignableFrom(type.getRawClass())
 			&&
 			EntityModel.class.isAssignableFrom(type.containedType(0).getRawClass());
 	}

src/main/java/org/springframework/hateoas/mediatype/collectionjson/Jackson2CollectionJsonModule.java

@@ -461,8 +461,7 @@ static class CollectionJsonPagedResourcesSerializer extends ContainerSerializer<
 		}
 
 		CollectionJsonPagedResourcesSerializer(@Nullable BeanProperty property) {
-
-			super(CollectionModel.class, false);
+			super(PagedModel.class, false);
 			this.property = property;
 		}
 

src/main/java/org/springframework/hateoas/mediatype/hal/CollectionModelMixin.java

@@ -27,7 +27,7 @@
 import com.fasterxml.jackson.databind.annotation.JsonSerialize;
 
 /**
- * Custom mixin to to render collection content as {@literal _embedded}.
+ * Custom mixin to render collection content as {@literal _embedded}.
  *
  * @author Alexander Baetz
  * @author Oliver Gierke

src/main/java/org/springframework/hateoas/mediatype/hal/Jackson2HalModule.java

@@ -37,6 +37,7 @@
 import org.springframework.hateoas.Link;
 import org.springframework.hateoas.LinkRelation;
 import org.springframework.hateoas.Links;
+import org.springframework.hateoas.PagedModel;
 import org.springframework.hateoas.RepresentationModel;
 import org.springframework.hateoas.mediatype.MessageResolver;
 import org.springframework.hateoas.mediatype.hal.HalConfiguration.RenderSingleLinks;
@@ -91,6 +92,7 @@ public Jackson2HalModule() {
 		setMixInAnnotation(Link.class, LinkMixin.class);
 		setMixInAnnotation(RepresentationModel.class, RepresentationModelMixin.class);
 		setMixInAnnotation(CollectionModel.class, CollectionModelMixin.class);
+		setMixInAnnotation(PagedModel.class, PagedModelMixin.class);
 	}
 
 	/**

src/main/java/org/springframework/hateoas/mediatype/hal/PagedModelMixin.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2012-2020 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.mediatype.hal;
+
+import java.util.Collection;
+
+import org.springframework.hateoas.PagedModel;
+
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.annotation.JsonInclude.Include;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonPropertyOrder;
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+
+
+/**
+ * Custom mixin to render collection content under {@literal _embedded} element.
+ *
+ * @author Patrick ALLAIN
+ */
+@JsonPropertyOrder({ "content", "links" })
+abstract class PagedModelMixin<T> extends PagedModel<T> {
+
+	@Override
+	@JsonProperty("_embedded")
+	@JsonInclude(Include.NON_EMPTY)
+	@JsonSerialize(using = Jackson2HalModule.HalResourcesSerializer.class)
+	@JsonDeserialize(using = Jackson2HalModule.HalResourcesDeserializer.class)
+	public abstract Collection<T> getContent();
+}

src/main/java/org/springframework/hateoas/mediatype/hal/forms/Jackson2HalFormsModule.java

@@ -110,8 +110,15 @@ abstract class CollectionModelMixin<T> extends CollectionModel<T> {
 		public abstract Collection<T> getContent();
 	}
 
+	@JsonSerialize(using = HalFormsCollectionModelSerializer.class)
 	abstract class PagedModelMixin<T> extends PagedModel<T> {
 
+		@Override
+		@JsonProperty("_embedded")
+		@JsonInclude(Include.NON_EMPTY)
+		@JsonDeserialize(using = HalFormsCollectionModelDeserializer.class)
+		public abstract Collection<T> getContent();
+
 		@Nullable
 		@Override
 		@JsonProperty("page")