Prometheus metrics endpoint missing Content-Type

According to the https://prometheus.io/docs/instrumenting/exposition_formats/#text-based-format HTTP responses are expected to contain Content-Type header with value 

text/plain; version=0.0.4

 (A missing version value will lead to a fall-back to the most recent text format version.)

I noticed this issue when trying to setup a scraper in InfluxDB 2 which expects the responses to contain the header as defined by the spec.

2023-11-01 09:58:50 ts=2023-11-01T07:58:50.778448Z lvl=error msg="Unable to gather" log_id=0l4KZHl0000 service=scraper scraper-name=Couchbase error="mime: no media type" 

Response headers sent by Couchbase /metrics endpoint:

HTTP/1.1 200 OK

Date: Wed, 01 Nov 2023 07:55:04 GMT

Server: MochiWeb/1.0 (Any of you quaids got a smint?)

Transfer-Encoding: chunked