How to set CERTIFICATE FILES as mandatory during application flow?

Neither the API nor the web frontend allows me to select files of type Diploma certificate as a required or optional document during the application flow.

But when retrieving the application over the API the following file types are supported:

CV, COVER_LETTER, OTHER, CERTIFICATE_OF_EMPLOYMENT, LETTER_OF_RECOMMENDATION, PORTFOLIO, CERTIFICATE, DIPLOMA, JOIN_CV

Can you please support these file types in the application flow (without forcing me to create a custom screening questions).