src/MultiLogger.php
public function getMonolog()
    {
        foreach ($this->loggers as $logger) {
            if (is_callable([$logger, 'getMonolog'])) {
                $monolog = $logger->getMonolog();

                if ($monolog === null) {
                    continue;
                }

                return $monolog;
            }
        }
    }
public function getMonolog()
    {
        foreach ($this->loggers as $logger) {
            if (is_callable([$logger, 'getMonolog'])) {
                $monolog = $logger->getMonolog();

                if ($monolog === null) {
                    continue;
                }

                return $monolog;
            }
        }
    }
Get the underlying Monolog instance.

@return \Monolog\Logger