Hi @nicasso,
Good Question.
I took the library files from another D7 site with the "mollie_payment" module working which was using the very same library.
I took a quick look and as you can see in the library files it's version 2.10.0 of the mollie-api-php library.
So, I didn't update them to the latest version.
As you can see the latest update should be 2.74.1 and you can update this by running the composer command:
$ composer require mollie/mollie-api-php:^2.0
So please give it a try. I assume this should also work.
But you know what they say about assumtions...
"Assumption is the mother of all f*ckups" ;)
For this particular use, and for the time being I did a rewrite of the 'commerce_mollie' module to use the Mollie API v2 for use with Drupal 7 Commerce.
Because I don't know how to write a patch properly, I share the compressed module folder 'commerce_mollie' so anyone who needs it can unzip it in their modules folder as usual.
The module now uses the Mollie API v2 library which is added in 'mollie-api-php'.
Unpack this one in your libraries folder and you should be good to go.
Please use it at your own risk and test it before, since I didn't had time to test it thorough.
vincent rommelaars → created an issue.