Logger       func(error)
	ErrorHandler func(http.ResponseWriter, *http.Request, error)

	// internal variables
	rewriter *headerRewriter
}

// NewForwarder creates an instance of Forwarder based on the provided list of configuration options
func NewForwarder(f *Forwarder) *Forwarder {
	f.rewriter = &headerRewriter{}
	if f.RoundTripper == nil {
		f.RoundTripper = http.DefaultTransport
	}

	return f
}