@Override
    public void setUpdateNeeded() {
        super.setUpdateNeeded();
        if (isGeneratedMipmapsRequired() && !hasMipmaps()) {
            // Mipmaps are no longer valid, since the image was changed.
            setMipmapsGenerated(false);
        }
    }
Sets the update needed flag, while also checking if mipmaps
need to be regenerated.
jme3-core/src/main/java/com/jme3/texture/Image.java