During deposit, filename is requested in the Content-Disposition header, when sending a binary/package. We then don't place any onus on the server to do anything with this information, and we don't provide any mechanism for this information to be included in the status document.
Is filename even meaningful? It MAY affect the @id that's given to the file, but it may also not.
What should we do? Get rid of filename in Content-Disposition, keep it and just document it's usage, or make space for it in the status.link field?