).toBlocking().single();         return new PagedList<FirewallPolicyInner>(response.body()) {             @Override             public Page<FirewallPolicyInner> nextPage(String nextPageLink) {                 return listNextSinglePageAsync(nextPageLink).toBlocking().single().body();             }         };     }      /**      * Gets all the Firewall Policies in a subscription.      *      * @param serviceCallback the async ServiceCallback to handle successful and failed responses.      * @throws IllegalArgumentException thrown if parameters fail the validation      * @return the {@link ServiceFuture} object      */     public ServiceFuture<List<FirewallPolicyInner>> list