/**
  * INTERNAL:
  * translate validation group specified as fully qualifed class names deliminated by ',' into Class[]
  * @param validationGroups Array of "," deliminated fully qualified class names
  * @param appClassLoader The classloader for application
  * @return Array of classes corresponding to classnames in given <code>validationGroups</code>.
  *         <code>null<code> if given <code>validationGroups</code> is null or empty
  */
 private Class[] translateValidationGroups(String validationGroups, ClassLoader appClassLoader) {
   Class[] validationGroupsClasses = null;
   if (validationGroups != null && validationGroups.length() != 0) {
     String[] validationGroupClassNames = validationGroups.split(",");
     validationGroupsClasses = new Class[validationGroupClassNames.length];
     for (int i = 0; i < validationGroupClassNames.length; i++) {
       String validationGroupClassName = validationGroupClassNames[i];
       try {
         validationGroupsClasses[i] = loadClass(validationGroupClassName, appClassLoader);
       } catch (Exception e) {
         throw PersistenceUnitLoadingException
             .exceptionLoadingClassWhileInitializingValidationGroups(
                 validationGroupClassName, e);
       }
     }
   }
   return validationGroupsClasses;
 }