getAggregation(oParent, sAggregationName) {
			const oAggregation = Utils.findAggregation(oParent, sAggregationName);
			if (oAggregation) {
				return oParent[oAggregation._sGetter]();
			}
			return undefined;
		}
Returns aggregation content for the given aggregation name.
@param {sap.ui.base.ManagedObject|Element} oParent - Control which has the aggregation
@param {string} sAggregationName - Aggregation name
@returns {sap.ui.base.ManagedObject[]|Element[]} Aggregation content