Fix SipSessionGroup from throwing ConcurrentModificationException

    }

    synchronized void onConnectivityChanged() {

        for (SipSessionImpl s : mSessionMap.values()) {

        SipSessionImpl[] ss = mSessionMap.values().toArray(

                    new SipSessionImpl[mSessionMap.size()]);

        // Iterate on the copied array instead of directly on mSessionMap to

        // avoid ConcurrentModificationException being thrown when

        // SipSessionImpl removes itself from mSessionMap in onError() in the

        // following loop.

        for (SipSessionImpl s : ss) {

            s.onError(SipErrorCode.DATA_CONNECTION_LOST,

                    "data connection lost");

        }