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