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I have a Prometheus-related question.

I expect the method label to appear consistently as GET and POST:

acs_go_http_requests_in_flight{method="GET",route="/ads/v1/mobile_leaderboard"} 0
acs_go_http_requests_in_flight{method="POST",route="/ads/v1/mobile_leaderboard"} 0
acs_go_http_requests_in_flight{method="GET",route="/ads/v1/promo_banner"} 0
acs_go_http_requests_in_flight{method="POST",route="/ads/v1/promo_banner"} 0
... and so on

However, in reality, the method label appears inconsistently, sometimes interchanging GET and POST. Occasionally, it even shows as GETT:

acs_go_http_requests_in_flight{method="GETT",route="/ads/v1/promo_banner"} 0

Here is a link to the relevant code:
middleware.go#L85-L121

I’ve seen a similar error message before, but I don’t think I’m registering the metric multiple times:

An error has occurred while serving metrics:
was collected before with the same name and label values

What could be causing this issue in my code?