* - userAgent A user agent, if you want to override the default
* MediaWiki/$wgVersion
* - logger A \Psr\Logger\LoggerInterface instance for debug logging
+ * - username Username for HTTP Basic Authentication
+ * - password Password for HTTP Basic Authentication
* @param string $caller The method making this request, for profiling
* @return string|bool (bool)false on failure or a string on success
*/