code: public Observable<ComapiResult<List<Participant>>> getParticipants(@NonNull final String conversationId) {
  
          final String token = getToken();
  
          if (sessionController.isCreatingSession()) {
              return getTaskQueue().queueGetParticipants(conversationId);
          } else if (TextUtils.isEmpty(token)) {
              return Observable.error(getSessionStateErrorDescription());
          } else {
              return doGetParticipants(token, conversationId);
          }
      }
docs: Returns observable to add a participant to.
  
  @param conversationId ID of a conversation to add a participant to.
  @return Observable to get a list of conversation participants.