public static interface FileDrop.TransferableObject.Fetcher

Instead of passing your data directly to the FileDrop.TransferableObject constructor, you may want to know exactly when your data was received in case you need to remove it from its source (or do anyting else to it). When the getTransferData(...) method is called on the FileDrop.TransferableObject, the FileDrop.TransferableObject.Fetcher's getObject() method will be called.