APEX Method to update cartDeliveryGroups

B2BCheckout.cls

public without sharing class B2BCheckout {
    @AuraEnabled
    public static CartDeliveryGroup setPickupInformation(String notes, String pickupTime, Id cartDeliveryGroupId) {
        CartDeliveryGroup cartDeliveryGroup = [
            SELECT Id, DeliveryMethodId
            FROM CartDeliveryGroup
            WHERE Id =: cartDeliveryGroupId
        ];
        Datetime desiredDeliveryDate = Datetime.valueOfGmt(pickupTime.replace('T', ' '));
        cartDeliveryGroup.ShippingInstructions = notes;
        cartDeliveryGroup.DesiredDeliveryDate = desiredDeliveryDate;
        update cartDeliveryGroup;
        return cartDeliveryGroup;
    }
}