lib/classes/Variables.js/Variables/populateValue
class Variables:  populateValue(valueToPopulate, root) {
    const property = valueToPopulate;
    const matches = this.getMatches(property);
    if (!_.isArray(matches)) {
      return BbPromise.resolve(property);
    }
    const populations = this.populateMatches(matches, valueToPopulate);
    return BbPromise.all(populations)
      .then(results => this.renderMatches(property, matches, results))
      .then(result => {
        if (root && matches.length) {
          return this.populateValue(result, root);
        }
        return result;
      });
  }