code: public static Object createInstanceAccordingToParameter(String parameterName,
                                                              Class<?>[] argClasses,
                                                              Object[] args,
                                                              Map<String, String> parameters)
              throws JournalException {
          String className = parameters.get(parameterName);
          if (className == null) {
              throw new JournalException("No parameter '" + parameterName + "'");
          }
          return createInstanceFromClassname(className, argClasses, args);
      }
docs: Look in the system parameters and create an instance of the named class.
  
  @param parameterName
  The name of the system parameter that contains the classname
  @param argClasses
  What types of arguments are required by the constructor?
  @param args
  Arguments to provide to the instance constructor.
  @param parameters
  The system parameters
  @return the new instance created