code: function(aDimensionName) {
  			this._oAggregationLevel = {};
  			if (!aDimensionName) {
  				aDimensionName = this._oQueryResult.getAllDimensionNames();
  			}
  			this.addToAggregationLevel(aDimensionName);
  			this._oSelectedPropertyNames = null; // reset previously compiled list of selected properties
  		}
docs: Set the aggregation level for the query result request. By default, the
  query result will include the properties holding the keys of the given
  dimensions. This setting can be changed using
  includeDimensionKeyTextAttributes.
  
  @param aDimensionName
  Array of dimension names to be part of the aggregation level.
  If null, the aggregation level includes all dimensions, if
  empty, no dimension is included.
  
  @public
  @function
  @name sap.ui.model.analytics.odata4analytics.QueryResultRequest#setAggregationLevel