protected void wakeupReader() {
        // If there are no pending messages then add one so that the
        // kernel-user knows to wake up if it is only listening for
        // envelopes.
        if( !hasEnvelopes() ) {
            // Note: this is not really a race condition.  At worst, our
            // event has already been handled, and it does no harm
            // to check again.
            addEnvelope( EVENTS_PENDING );
        }
    }
Contains the pending envelopes waiting for the caller to
 retrieve them.
jme3-networking/src/main/java/com/jme3/network/kernel/AbstractKernel.java