I used the spring-boot-starter-actuator jar in my project. After I upgraded the SpringBoot version from 2.5.5 to 2.5.6, when I visited the address of /actuator/prometheus through a browser, I found This address will become the form of the downloaded file (actually Content-Type is application/openmetrics-text) instead of the previous text/plain.

I carefully compared and debugged the related code, and found that the order of the two enumeration instances was adjusted in this submission (Fix broken content negotiation for Prometheus with OpenMetrics).

I think these two orders should be changed back to the previous order.

Comment From: wilkinsona

Thanks for the analysis. This is a duplicate of #28446.