What version of the Exporter are you using?

contrib.go.opencensus.io/exporter/stackdriver => contrib.go.opencensus.io/exporter/stackdriver v0.12.9-0.20191108183826-59d068f8d8ff

What version of OpenCensus are you using?

go.opencensus.io => go.opencensus.io v0.22.1

What version of Go are you using?

go version go1.14.2 linux/amd64

What did you do?

We have that count metric here https://github.com/google/knative-gcp/blob/d0a452483985c0f1d775efa2ea54fddaed2ed107/pkg/metrics/ingress_reporter.go#L59

Invoked here https://github.com/google/knative-gcp/blob/d0a452483985c0f1d775efa2ea54fddaed2ed107/pkg/metrics/ingress_reporter.go#L103

And we're seeing this error occasionally in our E2E tests that prevents our metrics from being uploaded

default-brokercell-ingress-594cd99c77-57gk6 ingress 2020/06/12 20:48:48 Failed to export to Stackdriver: rpc error: code = InvalidArgument desc = Field timeSeries[1].points[0].interval.start_time had an invalid value of "2020-06-12T13:48:47.794571-07:00": The start time must be before the end time (2020-06-12T13:48:47.794571-07:00) for the non-gauge metric 'knative.dev/internal/eventing/broker/event_count'.

If possible, provide a recipe for reproducing the error.
We have a continuous E2E test runs that occasionally run into this issue which is exercising the code path above https://testgrid.knative.dev/knative-gcp#continuous&include-filter-by-regex=TestGCPBrokerMetrics

What did you expect to see?

Metrics consistently uploaded to Stackdriver without this error

What did you see instead?

This error message

default-brokercell-ingress-594cd99c77-57gk6 ingress 2020/06/12 20:48:48 Failed to export to Stackdriver: rpc error: code = InvalidArgument desc = Field timeSeries[1].points[0].interval.start_time had an invalid value of "2020-06-12T13:48:47.794571-07:00": The start time must be before the end time (2020-06-12T13:48:47.794571-07:00) for the non-gauge metric 'knative.dev/internal/eventing/broker/event_count'.

Additional context

Add any other context about the problem here.