#vulnerable code 
                                void onJvbConferenceStopped(JvbConference jvbConference,
                                int reasonCode, String reason)
    {
        this.jvbConference = null;

        if (call != null)
        {
            hangUp(reasonCode, reason);
        }
        else
        {
            allCallsEnded();
        }
    } 
                            #location 8 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                void onConferenceCallInvited(Call incomingCall)
    {
        // Incoming SIP connection mode sets common conference here
        if (destination == null)
        {
            call.setConference(incomingCall.getConference());

            boolean useTranslator = incomingCall.getProtocolProvider()
                .getAccountID().getAccountPropertyBoolean(
                    ProtocolProviderFactory.USE_TRANSLATOR_IN_CONFERENCE,
                    false);
            CallPeer peer = incomingCall.getCallPeers().next();
            // if use translator is enabled add a ssrc rewriter
            if (useTranslator && !addSsrcRewriter(peer))
            {
                peer.addCallPeerListener(new CallPeerAdapter()
                {
                    @Override
                    public void peerStateChanged(CallPeerChangeEvent evt)
                    {
                        CallPeer peer = evt.getSourceCallPeer();
                        CallPeerState peerState = peer.getState();

                        if (CallPeerState.CONNECTED.equals(peerState))
                        {
                            peer.removeCallPeerListener(this);
                            addSsrcRewriter(peer);
                        }
                    }
                });
            }
        }
    }