Golang thrift continually adds the x/thrift content type

func (p *THttpClient) Flush() error {
	// Close any previous response body to avoid leaking connections.
	p.closeResponse()

	req, err := http.NewRequest("POST", p.url.String(), p.requestBuffer)
	if err != nil {
		return NewTTransportExceptionFromError(err)
	}
	p.header.Add("Content-Type", "application/x-thrift")
	req.Header = p.header
	response, err := p.client.Do(req)
	if err != nil {
		return NewTTransportExceptionFromError(err)
	}
	if response.StatusCode != http.StatusOK {
		// Close the response to avoid leaking file descriptors. closeResponse does
		// more than just call Close(), so temporarily assign it and reuse the logic.
		p.response = response
		p.closeResponse()

		// TODO(pomack) log bad response
		return NewTTransportException(UNKNOWN_TRANSPORT_EXCEPTION, "HTTP Response code: "+strconv.Itoa(response.StatusCode))
	}
	p.response = response
	return nil
}

 	p.header.Add("Content-Type", "application/x-thrift")