add(mPropertyBag) {
			if (!mPropertyBag.appId) {
				return Promise.reject("appId must be provided");
			}
			if (!mPropertyBag.change) {
				return Promise.reject("Change instance must be provided");
			}
			mPropertyBag.selector = {
				appId: mPropertyBag.appId
			};
			return PersistenceWriteAPI.add(mPropertyBag);
		}
Adds a descriptor inline change to the flex persistence.

@param {object} mPropertyBag - Object with parameters as properties
@param {string} mPropertyBag.appId - Reference app ID or an app variant ID
@param {sap.ui.fl.apply._internal.flexObjects.FlexObject} mPropertyBag.change - Change instance

@returns {Promise|sap.ui.fl.apply._internal.flexObjects.FlexObject} Promise resolves with the added change in persistence.
@private
@ui5-restricted