IssueTracker

Problem you have encountered:
I've created a task handler to handle HTTP cloud task.
When the handler returns a non 2XX response, for example 400, the task retires and get to the handler again with these headers:
x-cloudtasks-taskpreviousresponse
x-cloudtasks-taskretrycount
x-cloudtasks-taskretryreason

While x-cloudtasks-taskpreviousresponse, and x-cloudtasks-taskretrycount work as expected, and contain the retry count and the response returned by the handler in the previous run,  the x-cloudtasks-taskretryreason is always empty.

What you expected to happen:
I would expect to be able to control the value populated into x-cloudtasks-taskretryreason, based on the response returned by the handler (so the handler can use that information on the task's next retry).
For example, populate this header with the response body, in case of a non 2XX response


Steps to reproduce:
1. create an HTTP task that points to the handler
2. return a non 2XX response from the handler
3. get the task again in the handler, and check the headers mentioned above, x-cloudtasks-taskretryreason will be empty