Read message from file

[blagi]

Because of legacy application and PHP 7.1 I had to use php-imap v 4.1.2. I'd like to use some new features from latest versions like read message from file and did make changes to Message.php adding fromFile & fromString methods, and in ClientManager.php adding getMask(). While trying to use it I'm getting this Fatal error:

Uncaught Webklex\PHPIMAP\Exceptions\MaskNotFoundException: Unknown message mask provided in C:\git\austriataxi\vendor\webklex\php-imap\src\Message.php on line 326

In Message.php:

    $default_mask  = ClientManager::getMask("message");

$default-mask gets null value.

How can I set some default mask, or make somehow this to work?