Fix type of "load_relations" param

[danizord]

Hey @bakura10!

When trying to make a request loadnig additional relations, I got this error:

Validation errors: [load_relations] must be of type array

So this PR changes the descriptors to make "load_relations" a string (since json_encode transforns the array in string).

But unfortunately this does not fix my problem at all. Now I'm getting a 400 response because Guzzle is serializing the load_relations value like that: load_relations=%22%5B%5C%22Contact%5C%22%5D%22.
And Lighstpeed Retail API expects load_relations=["Contact"]. How can I tell Guzzle to serialize the value without encoding it?

[bakura10]

Hmmm... their serialization model is strange. It's not really an array (whcih should be load_relations[]="Contact") nor a string. It's really ugly but maybe you could try set it up as a string, remove the json_encode, and do that:

$client->foo('load_relations' => '["Contact"]');

Maybe you can try to use the $commandToRequest serializer (https://github.com/guzzle/guzzle-services/blob/master/src/GuzzleClient.php#L38) to decode the request ?

Or you can maybe try to use a custom query serializer: https://github.com/guzzle/guzzle-services/blob/master/src/QuerySerializer/QuerySerializerInterface.php ?

[danizord]

Ok, I'm taking the easy path for now and removing the json_encode filter. Opened #9 to fix that properly later.

Mergeable? :)

[danizord]

Meh, that does not fix the issue neither. Still serializing to load_relations=%22%5B%5C%22Contact%5C%22%5D%22.

Seems like we'll need to use a custom QuerySerializer anyway. I'll make a PR tomorrow.