presentParticipantsTracker = JsonCollections.createStringSet();
}
for (int i = 0; i < result.size(); i++) {
ParticipantUserDetails item = result.get(i);
UserDetails userDetails = item.getUserDetails();
String userId = userDetails.getUserId();
// Cache the participants' user details.
participantUserDetails.put(userId, userDetails);
clientIdToUserId.put(item.getParticipant().getId(), userId);