code: public String user(String property) {
  
          if (isNotInitialized()) {
              return getMessage(NOT_INITIALIZED);
          }
          try {
              return CmsJspTagUser.userTagAction(property, getRequest());
          } catch (Throwable t) {
              handleException(t);
          }
          CmsMessageContainer msgContainer = Messages.get().container(Messages.GUI_ERR_USER_PROP_READ_1, property);
          return getMessage(msgContainer);
      }
docs: Returns a selected user property, i.e. information about the currently
  logged in user, same as using
  the <code>&lt;cms:user property="***" /&gt;</code> tag.<p>
  
  @param property the user property to display, please see the tag documentation for valid options
  @return the value of the selected user property
  
  @see org.opencms.jsp.CmsJspTagUser