docs: function buildReferenceDefinition() {
      //Read the current configuration in the reference config.
      let referenceConf = refConfigAccessor.get();
      //Warn the user if empty.
      if (!referenceConf || isEmpty(referenceConf)) {
          console.warn('You did not set any reference list in the reference configuration, see Focus.reference.config.set.');
      }
      //Build an object from the keys.
      return Object.keys(referenceConf).reduce((acc, elt) => {
          acc[elt] = elt;
          return acc;
      }, {});
  }