private async Task <CacheKey> GetKey(Type resultType, Uri uri, IEnumerable <string> defaultVaryByHeaders, HttpRequestHeaders headers)
{
var parts = new List <string>
{
typeof(HttpResponseMessage).IsAssignableFrom(resultType) ? "Http" : "Typed",
uri?.ToString() ?? string.Empty
};
if (typeof(HttpResponseMessage).IsAssignableFrom(resultType))
{
var varyBy = await GetVaryByHeaders(uri, defaultVaryByHeaders);
parts.AddRange(headers.Where(h => varyBy.Any(v => v.Equals(h.Key, StringComparison.OrdinalIgnoreCase)))
.SelectMany(h => h.Value.Select(v => $"{UriHelpers.NormalizeHeader(h.Key)}:{UriHelpers.NormalizeHeader(v)}"))
.Distinct());
}
return(new CacheKey(string.Join("-", parts)));
}