private long getDisplay(int pos) {
        Displays displays = getDisplays();
        if (pos < displays.size()) return displays.get(pos).getDisplay();

        LOGGER.log(
            Level.SEVERE,
            "Couldn't locate Display requested in the list of Displays. pos:" +
            pos +
            " size: " +
            displays.size()
        );
        return glfwGetPrimaryMonitor();
    }
This routines return the display ID by position in an array of display returned
by glfwGetMonitors().

@param pos  the position of the display in the list of displays returned.
@return return the displayID if found otherwise return Primary display
jme3-lwjgl3/src/main/java/com/jme3/system/lwjgl/LwjglWindow.java