Please extend this and show how POST, PUT, and PATCH methods can be implemented for XML and JSON media types

[Behrang Saeedzadeh]

See this issue for more details.

It is not obvious how one should:

• Fetch the entity with a given ID from the reposiory
• Update its properties from the JSON/XML payload (PATCH)
• Replace the entity (PUT)
• Save it back to the repository