ReleaseNotes: 3.0.0-M3-Actuator Metrics Export Properties

[ashakirin]

We have moved the properties controlling the https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#actuator.metrics[actuator metrics export]. The old schema was management.metrics.export.<product>, the new one is management.<product>.metrics.export (Example: the prometheus properties moved from management.metrics.export.prometheus to management.prometheus.metrics.export). If you are using the spring-boot-properties-migrator, you will get notified at startup. See https://github.com/spring-projects/spring-boot/issues/30381[#30381] for details.