code: public void setConfig(String configName, String configValue)
    {
      if (config == null)
      {
        config = new Properties();
      }
  
      if(configValue == null)
      {
        config.remove(configName);
      }
      else
      {
        config.setProperty(configName, configValue);
      }
    }
docs: Add a new configuration. If the config name already exists, the config
  value is overwritten.
  
  @param configName The key of the config.
  @param configValue The value of the new config.