Variable ${sling.home} not replaced in configuration values

When configuring a file datastore, the variable ${sling.home} would be useful as showed in the following feature.json and in the Starter Pull Request (https://github.com/apache/sling-org-apache-sling-starter/pull/13)

{
"bundles":[
{
"id":"org.apache.jackrabbit:oak-segment-tar:${oak.version}",
"start-order":"15"
}
],
"configurations":{
"org.apache.jackrabbit.oak.segment.SegmentNodeStoreService":

{ "name":"Default NodeStore", "customBlobStore":true }

,
"org.apache.jackrabbit.oak.plugins.blob.datastore.FileDataStore": {
"minRecordLength":4096,
"path":"${sling.home}/repository/datastore",
"cacheSizeInMB":128
}
}
}

Running java -jar dependency/org.apache.sling.feature.launcher.jar -f slingfeature-tmp/feature-oak_tar.json -p sling

Results in a folder called ${sling.home}

➜ $ ls target
${sling.home} maven-archiver org.apache.sling.starter-12-SNAPSHOT-oak_tar_far.far sling
classes maven-shared-archive-resources org.apache.sling.starter-12-SNAPSHOT-sources.jar sling-slingfeature-maven-plugin-fmtmp
dependency maven-status org.apache.sling.starter-12-SNAPSHOT.jar slingfeature-tmp
generated-test-sources org.apache.sling.starter-12-SNAPSHOT-oak_mongo_far.far rat.txt test-classes