Fix > PHP Code Sniffer violation : null is not a valid PHP type

Author: lfluvisotto

app/code/Magento/Reports/Model/ResourceModel/Report/AbstractReport.php

@@ -57,7 +57,7 @@ abstract class AbstractReport extends \Magento\Framework\Model\ResourceModel\Db\
      * @param \Magento\Reports\Model\FlagFactory $reportsFlagFactory
      * @param \Magento\Framework\Stdlib\DateTime\Timezone\Validator $timezoneValidator
      * @param \Magento\Framework\Stdlib\DateTime\DateTime $dateTime
-     * @param null $connectionName
+     * @param string|null $connectionName
      */
     public function __construct(
         \Magento\Framework\Model\ResourceModel\Db\Context $context,