code: public final void setSession( AbstractSession session ) throws JMSException
      {
          if (session == null)
              this.sessionRef = null;
          else
          {
          	// Consistency check
          	if (sessionRef != null && sessionRef.get() != session)
          		throw new FFMQException("Message session already set","CONSISTENCY");
          		
              this.sessionRef = new WeakReference<>(session);
          }
      }
docs: Set the message session