The artemis-prometheus-metrics-plugin 2.2.0 sends blank Content-Type and cause the following error:

level=DEBUG source=scrape.go:1465 msg="Append failed" component="scrape manager" scrape_pool=serviceMonitor/myproject/broker-metrics/0 target=http://10.217.0.100:8161/metrics/ err="non-compliant scrape target sending blank Content-Type and no fallback_scrape_protocol specified for target"

This is because Prometheus v3 is more strict concerning the Content-Type header received when scraping. Prometheus v2 would default to the standard Prometheus text protocol if the target being scraped did not specify a Content-Type header or if the header was unparsable or unrecognised. This could lead to incorrect data being parsed in the scrape. Prometheus v3 will now fail the scrape in such cases. For further details see https://prometheus.io/docs/prometheus/3.0/migration/