func (a serviceOAuthAuthentication) authenticate(req *http.Request, endpoint string, params []byte) error {
	return nil // No additional headers needed for service OAuth requests
}
func (a serviceOAuthAuthentication) authenticate(req *http.Request, endpoint string, params []byte) error {
	return nil // No additional headers needed for service OAuth requests
}
// Service OAuth authentication requires no additional headers to be sent. The
// Coinbase Public Certificate is set as a TLS config in the http.Client