private JsonObject getCollaborator(String sessionId) {
JsonObject toRtn = collaborators.get(sessionId);
if (toRtn == null) {
String displyName = anonymousUsers.getDisplyName();
Collaborator collaborator =
new CollaboratorImpl(anonymousUsers.getUserId(), sessionId, displyName,
anonymousUsers.getColor(), false, true,
anonymousUsers.getPhotoUrl(displyName));
toRtn = new JsonObject(JacksonUtil.<JreJsonObject>convert(collaborator).toNative());
toRtn.removeField(Key.IS_ME);
collaborators.put(sessionId, toRtn);