Some connectors may need to be able to determine the MIME type for content, and there's currently no way in the connector API to do that. The 'dna-graph' project does have MimeTypeDetector interface, but that's meant as a lower-level interface for an implementation. MimeType was designed to be the main entry point for general components, but that's currently in 'dna-repository' (and connectors don't currently require that).