Kubernetes readiness probe endpoint returning 404

There appears to be some change in behaviour for the Kubernetes-oriented readiness group endpoint on 2.3.2 compared to 2.3.1.

For a service that has no external dependencies (and only readinessState in the health group), the /actuator/health/readiness endpoint is returning a 404.

Configuration we are using:

management.server.port=9083
management.health.probes.enabled=true
management.endpoints.enabled-by-default=false
management.endpoint.info.enabled=true
management.endpoint.health.enabled=true
management.endpoint.health.show-details=always
management.endpoint.health.group.liveness.include=livenessState,diskSpace,refreshScope
management.endpoint.health.group.readiness.include=readinessState
management.endpoint.health.group.liveness.show-details=always
management.endpoint.health.group.readiness.show-details=always
management.endpoints.web.exposure.include=health

Expected Behaviour We expect this to just return 200 with { "status": "UP" }

Actual Behaviour

$ http http://localhost:9083/actuator/health/readiness
HTTP/1.1 404 Not Found

Full health call:

$ http http://localhost:9083/actuator/health
HTTP/1.1 200 OK
Connection: keep-alive
Content-Type: application/json
Date: Sat, 25 Jul 2020 06:27:55 GMT
Transfer-Encoding: chunked

{
    "components": {
        "discoveryComposite": {
            "components": {
                "discoveryClient": {
                    "description": "Discovery Client not initialized",
                    "status": "UNKNOWN"
                }
            },
            "description": "Discovery Client not initialized",
            "status": "UNKNOWN"
        },
        "diskSpace": {
            "details": {
                "exists": true,
                "free": 287311962112,
                "threshold": 10485760,
                "total": 499963174912
            },
            "status": "UP"
        },
        "livenessStateProbeIndicator": {
            "status": "UP"
        },
        "ping": {
            "status": "UP"
        },
        "reactiveDiscoveryClients": {
            "components": {
                "Simple Reactive Discovery Client": {
                    "description": "Discovery Client not initialized",
                    "status": "UNKNOWN"
                }
            },
            "description": "Discovery Client not initialized",
            "status": "UNKNOWN"
        },
        "readinessStateProbeIndicator": {
            "status": "UP"
        },
        "refreshScope": {
            "status": "UP"
        }
    },
    "groups": [
        "liveness",
        "readiness"
    ],
    "status": "UP"
}

This may relate to #22107.