code: @Override
    public NetworkReqListener removeSessionListener(String sessionId) {
      if (this.localDataSource.exists(sessionId)) {
        return this.localDataSource.removeSessionListener(sessionId);
      }
      else if (!this.localMode && this.existReplicated(sessionId)) {
        // does not make much sense ;[
        this.makeLocal(sessionId);
        return this.localDataSource.removeSessionListener(sessionId);
      }
  
      return null;
    }
docs: /*
  (non-Javadoc)
  
  @see org.jdiameter.common.api.ha.ISessionDatasource#removeSessionListener( java.lang.String)