REST methods that can send HTTP body (POST, PATCH, PUT and DELETE) may take a single
parameter annotated as Body which will be encoded as HttpBody and sent as the body of HTTP request.
Such a method may not define any other body parameters (although it may take additional Path, Header
or Query parameters).
The single body parameter may have a completely custom encoding to HttpBody which may define its own MIME type
and doesn't necessarily have to be JSON.
REST methods that can send HTTP body (POST, PATCH, PUT and DELETE) may take a single parameter annotated as Body which will be encoded as HttpBody and sent as the body of HTTP request. Such a method may not define any other body parameters (although it may take additional Path, Header or Query parameters).
The single body parameter may have a completely custom encoding to HttpBody which may define its own MIME type and doesn't necessarily have to be JSON.