anchor.diff:  Combine policy is specified per configuration key/property, and the default in most cases is currently `replace`. The following
   keys have `merge` as default policy:
   
  -* docker.args
  -* docker.envBuild
  -* docker.envRun
  -* docker.labels
  -* docker.ports
  -* docker.tags
  +* `docker.args`
  +* `docker.envBuild`
  +* `docker.envRun`
  +* `docker.labels`
  +* `docker.ports`
  +* `docker.tags`
   
   This can be overridden individually for all configuration keys (of map/list type) by setting an additional property suffixed `._combine`.
   For example, to not merge ports, set `docker.ports._combine=replace`, and to enable merging of dns, set `docker.dns._combine=merge`.
  
positive.code: ----
  
  The behaviour will now be same as previous example.
  Note that you must explicitly state `<mode>override</mode>`, otherwise it will use the default `only`.
negative.code: | *docker.cpushares*
  | Set the proportion of the host machine's cpu cycles available to the container
  
  | *docker.cacheFrom.idx*
  | Defines a list of image names to use as cache sources. See <<list-properties>>.
  
  | *docker.domainname*
  | Container domain name
  
  | *docker.dns.idx*
  | List of dns servers to use. See <<list-properties>>.
  
  | *docker.dnsSearch.idx*
  | List of dns search domains. See <<list-properties>>.
  
  | *docker.dockerArchive*
  | specify an archive which can be loaded with `docker load`. Use this as an alternative to `docker.dockerFile` or `docker.dockerFileDir`
  