fixes #7802, when api version 1.11 is `json.Marshal`ing the container st...

fixes #7802, when api version 1.11 is `json.Marshal`ing the container struct

Signed-off-by: Jessica Frazelle <jfrazelle@users.noreply.github.com>
It is pretty confusing to have named returns in this case, because I always need to look what the hell is body now. I prefer to return just `nil` instead of `body` on errors.