@Override
    public void create(boolean waitFor) {
        if (created.get()) {
            logger.warning("create() called when NullContext is already created!");
            return;
        }

        new Thread(this, THREAD_NAME).start();
        if (waitFor) waitFor(true);
    }
Accesses the listener that receives events related to this context.

@return the pre-existing instance
jme3-core/src/main/java/com/jme3/system/NullContext.java