code: private String getMandatory(String name) {
          if (!config.containsKey(name)) {
              throw new ProbeConfigurationException(name + " parameter is missing.");
          } else {
              return config.getString(name);
          }
  
      }
docs: Enforce the fact that a parameter is mandatory
  
  @param name The name of the parameter
  @return The value found
  @throws ConfigurationException When a mandatory parameter is missing