Custom content list marshaller/unmarshaller to dom4j representation. This
allows you to mix data binding and document model representations for XML
within the same application. You simply use this marshaller/unmarshaller with
a linked object type that implements java.util.List (the actual
runtime type - the declared type is ignored and can be anything). When
unmarshalling it will create an instance of java.util.ArrayList
if a list is not passed in and any content is present, then return all the
content up to the close tag for the enclosing element in the list. When
marshalling, it will simply write out any content directly.