public interface Manifest
TODO In the future, we may want to make this an abstract base class and add a SerializerDictionary that maps keys to Serializers. Local manifests can use the dictionary to write data out to the native OS, and remote manifests can do the opposite. We'll still need a means of mapping value keys to native IDs (which we would need to do via MIME types if the system is based on AWT's DnD mechanism).
boolean containsValue(String key)