Issues with jackson serialization of `org.springframework.data.web.PagedModel`

[ghferrari]

In a Spring Boot @RestController, a response of org.springframework.data.web.PagedModel<T> is currently serialized differently from a response of type List<T> . In particular, if polymorphic serialization is specified for type <T> via JsonTypeInfo and JsonSubTypes, these will be applied for List<T> but not currently for PagedModel<T>. This results in behaviour that is unexpected which also leaves one with no simple way of achieving polymorphic serialization while using PagedModel.

The default serialization configuration for Spring framework depends closely on this code from Spring Framework's AbstractJackson2HttpMessageConverter.java.

if (type != null && TypeUtils.isAssignable(type, value.getClass())) {
    javaType = getJavaType(type, null);
}

With this default code from Spring Framework, PagedModel<T> is classified as a SimpleType, while List<T> is defined as a CollectionType. This then impacts Spring Framework's choice of ObjectWriter.

It would be helpful if Spring Data supplied (and maintained) the additional Jackson configuration that is needed to ensure that PagedModel<T> will serialize similarly in relevant ways to List<T>.