code: function() {
      this._super.apply(this, arguments);
      this._options = _.defaults({}, this._options);
  
      // apply complex defaults to options
      if (this._options.join) {
        this._options.through = this._options.join;
      }
      if (this._options.through) {
        this._options.through = inflection.pluralize(this._options.through);
        this._options.through = _.camelCase(this._options.through);
      }
    }
docs: Override of {@link BaseRelation#init}.
  
  @method
  @protected
  @param {String} [options.join] Simply an alias for join.
  @see {@link BaseRelation#init}