code: public static SparkDataClient getDataClient(String clientName)
      {
  
          if (clientPool.get(clientName) != null)
          {
              return clientPool.get(clientName);
          }
          try
          {
              SparkDataClient dataClient = (SparkDataClient) KunderaCoreUtils.createNewInstance(Class
                      .forName(clientNameToClass.get(clientName)));
              clientPool.put(clientName, dataClient);
              return dataClient;
          }
          catch (Exception e)
          {
              logger.error(clientName
                      + " client is invalid/not supported. Please check kundera.client in persistence properties.");
              throw new KunderaException(clientName
                      + " client is invalid/not supported. Please check kundera.client in persistence properties.");
          }
      }
docs: Gets the data client.
  
  @param clientName
  the client name
  @return the data client