Field mediaType missing from manifest.json

[kachamaka]

As per docker specifications: https://github.com/openshift/docker-distribution/blob/main/docs/spec/manifest-v2-2.md#manifest-list-field-descriptions
the medieType field is not strictly required, however, it is usually always present in the majority of images I have observed.

This is missing in the manifest json of the x509-certificate-exporter manifest.json.
I also had difficulties with an OCI transport because this field was missing.

Is it possible to add this?

Thanks