docs: @Override
      public Object getAttribute(
              HttpServletRequest httpServletRequest,
              PortletWindow plutoPortletWindow,
              String attributeName) {
          if (IPortletRenderer.MULTIVALUED_USERINFO_MAP_ATTRIBUTE.equals(attributeName)) {
  
              // Get the list of user attributes the portal knows about the user
              final String remoteUser = httpServletRequest.getRemoteUser();
              if (remoteUser == null) {
                  return null;
              }
  
              final IPortletWindow portletWindow =
                      this.portletWindowRegistry.convertPortletWindow(
                              httpServletRequest, plutoPortletWindow);
              final List<? extends UserAttribute> expectedUserAttributes =
                      this.getExpectedUserAttributes(httpServletRequest, portletWindow);
  
              return getMultiValuedUserInfoMap(remoteUser, expectedUserAttributes);
          }
  
          return null;
      }