func (pool *DopplerPool) getClient(key, url string) loggregatorclient.Client {
	var client loggregatorclient.Client
	if client = pool.clients[key]; client == nil {
		return nil
	}

	// scheme://address
	if !((len(url) == len(client.Scheme())+3+len(client.Address())) &&
		strings.HasPrefix(url, client.Scheme()) && strings.HasSuffix(url, client.Address())) {
		return nil
	}

	return client
}