private void initDisplay() {
        // acquire important objects
        // from the context
        settings = context.getSettings();

        // Only reset the timer if a user has not already provided one
        if (timer == null) {
            timer = context.getTimer();
        }

        renderer = context.getRenderer();
    }
Sets the Timer implementation that will be used for calculating
frame times.  By default, Application will use the Timer as returned
by the current JmeContext implementation.
jme3-core/src/main/java/com/jme3/app/LegacyApplication.java