Comment 7 for bug 1835186

I am not entirely sure but it seems that cinder internally needs only the volume type id when updating or deleting encryption type [1][2][3]. When an encryption type is created via the API it must be connected to a volume type which suggests that volume type id should be enough for identifying the encryption type.

Also when the /v3/{project_id}/types/{volume_type_id}/encryption/{encryption_id} request is send with valid values for {project_id} and {volume_type_id} the request will pass as long as {encryption_id} contains any value (e.g. "abcd") and the volume type has an encryption type.

[1] https://github.com/openstack/cinder/blob/4580c56058a39726dd174b1aefa7b3eacc63904c/cinder/api/contrib/volume_type_encryption.py#L113
[2] https://github.com/openstack/cinder/blob/4580c56058a39726dd174b1aefa7b3eacc63904c/cinder/api/contrib/volume_type_encryption.py#L151
[3] https://github.com/openstack/cinder/blob/e8f03523e8d244fb9c1ecceb091784cc37d63b0d/cinder/db/api.py#L873