/// <summary>
/// Retrieves the secret from the cache, if not present calls the underlying <see cref="ISecretRepository"/> to acquire and caches the result.
/// </summary>
/// <param name="clientId"></param>
/// <returns></returns>
public string ClientSecret(string clientId)
{
var key = CacheRegion.CacheKey(clientId);
return(cachePolicy.Cache(key, () => Task.FromResult(repository.ClientSecret(clientId))).GetAwaiter().GetResult());
}