This change makes it possible to declare an @RequestBody argument with
a generic type (e.g. List<Foo>). If a GenericHttpMessageConverter
implementation supports the method argument, then the request will be
converted to the apropiate target type.
The new GenericHttpMessageConverter is implemented by the
MappingJacksonHttpMessageConverter and also by a new
Jaxb2CollectionHttpMessageConverter that can read read a generic
Collection where the generic type is a JAXB type annotated with
@XmlRootElement or @XmlType.
Issue: SPR-9570
c9b7b132fb