See https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#application-properties.actuator.management.endpoint.configprops.show-values for example. They all default to NEVER.
There are three of them: management.endpoint.configprops.show-values, management.endpoint.env.show-values and management.endpoint.quartz.show-values.
Comment From: mhalbritter
This can be done by adding an entry in spring-boot-project/spring-boot-actuator-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json. You can take management.prometheus.metrics.export.histogram-flavor (the backing code is org.springframework.boot.actuate.autoconfigure.metrics.export.prometheus.PrometheusProperties#histogramFlavor) for a blueprint, it's an enum with a default, too.
Comment From: scottfrederick
Closing in favor of #39589.