return null;
}
DocumentFile<MongoType> df = new DocumentFile<MongoType>(id, file.getFilename(), file.getInputStream(), (String)file.get(STAGE_KEY), file.getUploadDate());
if(file.containsField(MIMETYPE_KEY)) {
df.setMimetype((String) file.get(MIMETYPE_KEY));
}
if(file.containsField(ENCODING_KEY)) {
df.setEncoding((String) file.get(ENCODING_KEY));