type HTTPBodyMarshaler … // ContentType returns its specified content type in case v is a // google.api.HttpBody message, otherwise it will fall back to the default Marshalers // content type. func (h *HTTPBodyMarshaler) ContentType(v interface{ … } // Marshal marshals "v" by returning the body bytes if v is a // google.api.HttpBody message, otherwise it falls back to the default Marshaler. func (h *HTTPBodyMarshaler) Marshal(v interface{ … }