== what Kubernetes actually mounts ==
$ find /tmp/demo-configmap /tmp/demo-secret -type f | sort
<configmap-mount>/demo.datasource-url
<configmap-mount>/demo.greeting
<configmap-mount>/demo.pool-size
<configmap-mount>/demo/nested/value
<secret-mount>/demo.api-key

$ cat <configmap-mount>/demo.greeting; echo
from-configmap-volume

Each file holds a bare value with no trailing newline and no key. There is no
properties syntax to parse -- the filename is the key.

== importing it ==
$ java -jar target/profiles-and-config-1.0.0.jar \
    --spring.config.import=configtree:/tmp/demo-configmap/,configtree:/tmp/demo-secret/

  active profiles : (none)
  effective value : from-configmap-volume
    1. from-configmap-volume              <- ConfigTreePropertySource {name='Config tree '/tmp/demo-configmap''}
    2. from-application-yaml              <- 'file application.yaml' via location 'optional:classpath:/''}
  holders that lost: 1

  demo.pool-size      = 25
  demo.nested.value   = from-nested-directory
  demo.api-key        = sk_live_not_a_real_key

A directory under the mount becomes a nested property: demo/nested/value is
demo.nested.value. That is how a ConfigMap with slashes in its keys arrives.

== the part that surprises people ==
An imported config tree outranks application.yaml, but it is still config data,
so it still loses to an environment variable:

  active profiles : (none)
  effective value : from-environment-variable
    1. from-environment-variable          <- OriginAwareSystemEnvironmentPropertySource {name='systemEnvironment'}
    2. from-configmap-volume              <- ConfigTreePropertySource {name='Config tree '/tmp/demo-configmap''}
    3. from-application-yaml              <- 'file application.yaml' via location 'optional:classpath:/''}
  holders that lost: 2

There is also no such thing as a profile-specific config tree. There is no
<mount>-prod directory convention; a per-environment ConfigMap is a different mount
chosen by the deployment, not by spring.profiles.active.