CI/CD system doesn't resolve environment variables

Using this plugin, I am able to easily keep my API keys locally and not upload them via git.

However, when using the Gitlab CI system to deliver application via runners, this plugin doesn't resolve the keys in environment variables defined in Gitlab (ORG_GRADLE_PROJECT_) and defaults to using the default variables in the specified file (local.defaults.properties for example).

The expected behaviour is:

- Check for the given properties file (local.properties)
- Check environment variables
- Use the default properties file (local.defaults.properties)