code: private void addClasses(Class<?>[] classes, HashSet<Class<?>> result, String fieldName){
  		
  		if(classes == null || classes.length==0)	
  			Error.classesAbsent(fieldName, configuredClass);
  		
  		for (Class<?> classe : classes)	result.add(classe);
  	}
docs: Adds to the result parameter all classes that aren't present in it
  @param classes classes to control
  @param result List to enrich
  @param fieldName name of file, only for control purpose