code: public Observable<FirewallRuleInner> updateAsync(String resourceGroupName, String accountName, String firewallRuleName, UpdateFirewallRuleParameters parameters) {
          return updateWithServiceResponseAsync(resourceGroupName, accountName, firewallRuleName, parameters).map(new Func1<ServiceResponse<FirewallRuleInner>, FirewallRuleInner>() {
              @Override
              public FirewallRuleInner call(ServiceResponse<FirewallRuleInner> response) {
                  return response.body();
              }
          });
      }
docs: Updates the specified firewall rule.
  
  @param resourceGroupName The name of the Azure resource group.
  @param accountName The name of the Data Lake Store account.
  @param firewallRuleName The name of the firewall rule to update.
  @param parameters Parameters supplied to update the firewall rule.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the FirewallRuleInner object