lib/classes/Variables.js/Variables/populateObjectImpl
class Variables:  populateObjectImpl(objectToPopulate) {
    const leaves = this.getProperties(objectToPopulate, true, objectToPopulate);
    const populations = this.populateVariables(leaves);
    if (populations.length === 0) {
      return BbPromise.resolve(objectToPopulate);
    }
    return this.assignProperties(objectToPopulate, populations)
      .then(() => this.populateObjectImpl(objectToPopulate));
  }