Yes! It works 200%. Thanks.
Updated code:
Content content = localTaskService.getContent(documentContentId);
System.out.println(content.getId() + " => " + content.toString());
if (content != null){
Object obj = ContentMarshallerHelper.unmarshall(content.getContent(), null);
System.out.println("Object = " + obj.getClass());
System.out.println("Object.2String() = " + obj.toString());
}