I have a RestResource class that is called by our backend to perform a specific action. The problem is that when I attempt to test for this class, I run into a snag. The Class accepts a JSON file from our backend and puts into a custom list I create within the class. Here's a snippet:

    @RestResource(urlMapping='/restEndpoint/*')
    global with sharing class Ecomm_Webhook_Rest {
    global class Subscription {
		public String itemId;
		public String licenseId;
		public Integer quantity;
		public String interval;
		public String sku;
	}
	global class RemovedSubscription {
		public String removedId;
	}
	
    @HttpPost
    global static void determineWhatNeedsToBeUpdated(
    List<Subscription> subscriptions, 
    List<RemovedSubscription> removedSubscriptions,
    ) { // code here
    }

The test method I've attempted:

    static testMethod void test() {
        List<Ecomm_Webhook_Rest.Subscription> subs = new List<restClass.Subscription>();
        List<Ecomm_Webhook_Rest.RemovedSubscription> removed = new List<restClass.RemovedSubscription>();
        
        Ecomm_Webhook_Rest.determineWhatNeedsToBeUpdated(subs, removed);
        
    }
    }

I've attempted different lists to send, but each time I keep getting incorrect signature. What could I do to solve this?