code: public void setActionClass(String value) {
  
          checkFrozen();
          if (CmsStringUtil.isEmpty(value)) {
              m_actionClass = null;
          } else {
              if (!CmsStringUtil.isValidJavaClassName(value)) {
                  throw new CmsIllegalArgumentException(
                      Messages.get().container(Messages.ERR_MODULE_ACTION_CLASS_2, value, getName()));
              }
              m_actionClass = value;
          }
      }
docs: Sets the class name of this modules (optional) action class.<p>
  
  Providing <code>null</code> as a value indicates that this module does not use an action class.<p>
  
  <i>Please note:</i>It's not possible to set the action class name once the module
  configuration has been frozen.<p>
  
  @param value the class name of this modules (optional) action class to set