Having problems using third-party vendors in my module

[adid01nete33ad]

Hello there!

I created a module for Magento2 and now need to include some 3d-party vendors.

I've read multiple posts about achieving this. I have tried these, but I can't get it to work correctly.

Adding the autoload.php to the composer.json of the modul

"autoload": {
        "files": [
            "registration.php",
            "thrdParty/vendor/autoload.php"
        ]
    }

Or adding the autoload.php directly to the registration.php

require_once "thrdParty/vendor/autoload.php";

Both methods work in so far that I can use said vendors in my module. However, when I run the compile command, I get an error "Interface ... not found#0".

 php bin/magento setup:di:compile

I guess I could add the vendors to the Magento2 composer.json file, but that doesn't seem like a good practice.

I would be grateful for any help/insights!