What did you do?
Scraping the Prometheus endpoint of a service.

What did you expect to see?
Prometheus uses the following Accept header:
Accept: application/openmetrics-text; version=1.0.0,text/plain;version=0.0.4;q=0.5,*/*;q=0.1
Please notice that the version is 1.0.0 for application/openmetrics-text.

What did you see instead? Under which circumstances?
Accept: application/openmetrics-text; version=0.0.1,text/plain;version=0.0.4;q=0.5,*/*;q=0.1
Please notice that the version is 0.0.1 for application/openmetrics-text.

As @fstab pointed out in a connected issue(prometheus/client_java#702 (comment)), Prometheus should use 1.0.0 according to OpenMetrics specs.

Environment
My locally built prometheus instance or using the latest Docker image.

• System information:
  Darwin 20.6.0 x86_64 or latest Docker image

• Prometheus version:
  2.30.0 (latest docker image) or locally build instance from main

• Alertmanager version:
  I don't think it is relevant.

• Prometheus configuration file:

global:
    scrape_interval: 10s
    evaluation_interval: 10s

scrape_configs:
    - job_name: 'prometheus'
      static_configs:
          - targets: ['localhost:9090']
    - job_name: 'webservices'
      metrics_path: '/actuator/prometheus'
      static_configs:
          - targets: ['localhost:8080']

• Alertmanager configuration file:
  I don't think it is relevant.

• Logs:
  I don't think it is relevant.