public with sharing class webhookClass{
    public cls_webhook webhook;
    public class cls_webhook {
        public String topic;  //customers/create
        public String address; // https://hicsfshopify-developer-edition.ap4.force.com/services/apexrest/UpdateCustomerFromShopify/
        public String format; //json
        public String id; 
        public Object[] metafield_namespaces;  //json
    }
    public static webhookClass parse(String json){
        return (webhookClass) System.JSON.deserialize(json, webhookClass.class);
    }
}