We are not allow users to use correct media types as specified by the RFCs we are implementing:

• RootResourceDiscoveryService does not produce application/json
• RestconfServices does not produce application/yang-data+xml
• RestconfOperationsService does not produce application/yang-data+xml

Also the patch operations are using media types from draft-ietf-netconf-yang-patch-08, which have changed from draft-ietf-netconf-yang-patch-09 onwards.

Add the appropriate types.