onElementOverlayCreated = function(oEvent) {
					var oElementOverlay = oEvent.getParameter("elementOverlay");
					if (oElementOverlay.getElement().getId() === oParent.getId()) {
						var oParentAggregationOverlay = oElementOverlay.getAggregationOverlay(sAggregationName);
						this.detachElementOverlayCreated(onElementOverlayCreated, this);
						this._addAggregation(oElement, oParentAggregationOverlay);
					}
				}
Creates an ElementOverlay (if doesn't exist) and adds it to specified aggregation of the parent
@param {sap.ui.core.Element} oElement - Element which was added
@param {sap.ui.core.Element} oParent - Parent element
@param {string} sAggregationName - Aggregation name
@private