Blogpost doctype definition prototype is missing two properties

The blogpost document type definition is missing two properties. The node at /hippo:namespaces/<mynamespace>/blogpost/hipposysedit:prototypes/hipposysedit:prototype must have a string property "hippostd:holder" with value "holder". It should also have a String property "hippostd:stateSummary" with value "new".

If the holder property is missing, creating content in the channel manager for this document type fails. No problems when creating a document in the Content perspective.

I checked other properties of this document type in comparison with a type freshly created in the document type editor: I couldn't find any other missing or misconfigured property.