API4KP11 — Missing/Default content types may break PSM implementations

Reproducer:
Api spec - KnowledgeAssetRepository :: addCanonicalKnowledgeAssetSurrogate

the body parameter does not specify a content type, which is defaulted to /. Swagger-CodeGenerated clients pass the value to the server, but the server may reject any payload that does not have an explicit content type.
This behavior has been verified with Spring-Web (2.7), but also (independently) with some enterprise firewall rules.

Either way, the spec should be explicit, and the use of content types should be reviewed across the 5 OpenApi documents