@Override
    public void resetObject() {
        this.id = -1;
        for (ShaderSource source : shaderSourceList){
            source.resetObject();
        }
        setUpdateNeeded();
    }
Called by the object manager to reset all object IDs. This causes
the shader to be reuploaded to the GPU in case the display was restarted.
jme3-core/src/main/java/com/jme3/shader/Shader.java