Its not obvious but it would be nice to make it easier to see.

Without clicking on the value cell, it looks like a single value parameter.

When I click on the cell, I see both the drop down and the ellipsis menu. Since there is a default value for MIME_TYPE, user would just populate the drop down and can easily ignore the mime-type.

A further enhancement to this would be to make mime_type configured to an Attribute Value choice similar to “value”. If this is available, then I can add a MimeTypeFinder transformer in my workflow to populate the Mime-type parameter of the Multipart Upload.

The use case for this would be when using the AddAttachments REST API and a feature with multiple attachments of different mime types supported by the destination format, eg, AGOL and Portal format writers.