Это должно работать:

javax.naming.Context context = new javax.naming.InitialContext();
PortletServiceHome portletServiceHome = (PortletServiceHome) context.lookup( "portletservice/com.ibm.portal.um.portletservice.PumaHome");
if (portletServiceHome != null) {
com.ibm.portal.um.portletservice.PumaHome pumaHome = (PumaHome) portletServiceHome.getPortletService(PumaHome.class);
com.ibm.portal.um.PumaLocator pumaLocator = pumaHome.getLocator(request);
com.ibm.portal.um.PumaProfile pumaProfile = pumaHome.getProfile(request);

List<com.ibm.portal.um.Group> user_groups_list = pumaLocator.findGroupsByAttribute("cn", "*");

List<String> attribG = new ArrayList<String>();
attribG.add("cn");

List<String> attribU = new ArrayList<String>();
attribU.add("uid");

for (Iterator<Group> iterator1 = user_groups_list.iterator(); iterator1.hasNext();) {

Group group = (Group) iterator1.next();
Map<String, Object> group_attribs = pumaProfile.getAttributes(group, attribG );
String group_cn = (String) group_attribs.get((Object)"cn");

System.out.println("group cn: " + group_cn);

List<Principal> listUsers = pumaLocator.findMembersByGroup(group, false);

for (Iterator<Principal> iterator2 = listUsers.iterator(); iterator2.hasNext();) {
Principal principal = (Principal) iterator2.next();

Map<String, Object> user_attribs = pumaProfile.getAttributes(principal, attribU );
String user_uid = (String) user_attribs.get((Object)"uid");

System.out.println("uid = " + user_uid);
}

}
}

Только из HttpServletRequest