update(/* mPropertyBag */) {
			return Promise.reject("write is not implemented");
		}
Interface called to update an existing flex data.

@param {object} mPropertyBag Property bag
@param {object} mPropertyBag.flexObject Flex Object to be updated
@param {sap.ui.fl.Layer} mPropertyBag.layer Layer on which the data should be updated
@param {string} [mPropertyBag.transport] The transport ID
@param {string} [mPropertyBag.url] Configured url for the connector
@returns {Promise} Resolves as soon as the writing is completed without data