function _doSingleWrite(mPropertyBag) {
		mPropertyBag.fileName = mPropertyBag.flexObject.fileName;
		return _doWrite.call(this, mPropertyBag);
	}
Send request to a back end to write or update a single flex data.

@param {object} mPropertyBag - Property bag
@param {string} mPropertyBag.method - POST for writing new data and PUT for update an existing data
@param {object} mPropertyBag.flexObject - Object to be updated
@param {string} mPropertyBag.url - Configured url for the connector
@returns {Promise} Promise resolves as soon as the writing was completed