code: public ServiceFuture<Void> beginOnlineRegionAsync(String resourceGroupName, String accountName, String region, final ServiceCallback<Void> serviceCallback) {
          return ServiceFuture.fromResponse(beginOnlineRegionWithServiceResponseAsync(resourceGroupName, accountName, region), serviceCallback);
      }
docs: Online the specified region for the specified Azure Cosmos DB database account.
  
  @param resourceGroupName Name of an Azure resource group.
  @param accountName Cosmos DB database account name.
  @param region Cosmos DB region, with spaces between words and each word capitalized.
  @param serviceCallback the async ServiceCallback to handle successful and failed responses.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceFuture} object