The latest(2.30.0) version of Prometheus sends out the following request when scraping:

GET /actuator/prometheus HTTP/1.1
Host: host.docker.internal:8080
User-Agent: Prometheus/2.30.0
Accept: application/openmetrics-text; version=0.0.1,text/plain;version=0.0.4;q=0.5,*/*;q=0.1
Accept-Encoding: gzip
X-Prometheus-Scrape-Timeout-Seconds: 10

In the Accept header, the version of openmetrics-text is 0.0.1 (see scrape.go).
In the Java client, the Content-Type constant does not match to this, its version is 1.0.0 (see TextFormat):

CONTENT_TYPE_OPENMETRICS_100 = "application/openmetrics-text; version=1.0.0; charset=utf-8";

The python client uses 0.0.1 too. Shouldn't all use the same version (1.0.0) or should the Java client use (0.0.1)?

It also seems that TextFormat::chooseContentType takes this into account: