code: public Observable<FirewallRuleInner> replaceAsync(String resourceGroupName, String serverName) {
          return replaceWithServiceResponseAsync(resourceGroupName, serverName).map(new Func1<ServiceResponse<FirewallRuleInner>, FirewallRuleInner>() {
              @Override
              public FirewallRuleInner call(ServiceResponse<FirewallRuleInner> response) {
                  return response.body();
              }
          });
      }
docs: Replaces all firewall rules on the server.
  
  @param resourceGroupName The name of the resource group that contains the resource. You can obtain this value from the Azure Resource Manager API or the portal.
  @param serverName The name of the server.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the FirewallRuleInner object