update(mPropertyBag) {
			mPropertyBag.method = "PUT";
			return _doSingleWrite.call(this, mPropertyBag);
		}
Update an existing flex data stored in the back end.

@param {object} mPropertyBag - Property bag
@param {object} mPropertyBag.flexObject - Flex Object to be updated
@param {string} mPropertyBag.url - Configured url for the connector
@returns {Promise} Resolves as soon as the writing is completed without data