code: public Observable<Void> regenerateKeyAsync(String resourceGroupName, String accountName, KeyKind keyKind) {
          return regenerateKeyWithServiceResponseAsync(resourceGroupName, accountName, keyKind).map(new Func1<ServiceResponse<Void>, Void>() {
              @Override
              public Void call(ServiceResponse<Void> response) {
                  return response.body();
              }
          });
      }
docs: Regenerates an access key for the specified Azure Cosmos DB database account.
  
  @param resourceGroupName Name of an Azure resource group.
  @param accountName Cosmos DB database account name.
  @param keyKind The access key to regenerate. Possible values include: 'primary', 'secondary', 'primaryReadonly', 'secondaryReadonly'
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable for the request