protected override IEnumerator DoExecuteCoroutine(TaskExecutionContext context)
{
var headers = context.Get<Dictionary<string, string>>(HeaderKey);
var url = (string)context[UrlKey];
using (var www = new WWW(url, null, headers))
{
var progressReporter = ProgressCallback(_progressKey, context.OnProgress);
yield return WwwHelper.GetResponse(www, context.CancellationToken, (string)context[HashKey], progressReporter);
context[ResultKey] = www.text;
}
}