public class Assets implements Disposable, AssetErrorListener {

    public static final Assets instance = new Assets();

    private AssetManager assetManager;

    public AssetPlayItems playItems;

    public Skin skinGameUI;

    public void initQueue (AssetManager assetManager) {
        this.assetManager = assetManager;
        // set asset manager error handler
        assetManager.setErrorListener(this);
        // load texture atlas
        assetManager.load(Constants.TEXTURE_PLAY_GAME, TextureAtlas.class);


        //load skins
        assetManager.load(Constants.SKIN_GAME_UI, Skin.class, new SkinLoader.SkinParameter(Constants.TEXTURE_GAME_UI));

        //load spine
        assetManager.load(Constants.SKELETON_DATA,  SkeletonData.class);
        assetManager.load(Constants.TEXTURE,  TextureAtlas.class);

    }

    public void get(){

        assetManager.finishLoading();
        TextureAtlas atlasPlayMain = assetManager.get(Constants.TEXTURE_PLAY_GAME);

        skinGameUI = assetManager.get(Constants.SKIN_GAME_UI);

        TextureAtlas atlas = assetManager.get(Constants.TEXTURE);
        //SkeletonData skeletonData = assetManager.get(Constants.SKELETON_DATA);

        // enable texture filtering for pixel smoothing
        for (Texture t : atlasPlayMain.getTextures()) {
            t.setFilter(TextureFilter.Linear, TextureFilter.Linear);
        }

        playItems = new AssetPlayItems(atlasPlayMain);
    }


    public class AssetPlayItems {

        public final AtlasRegion levelBackground;

        public AssetPlayItems (TextureAtlas atlas) {

            levelBackground =  atlas.findRegion("background");

        }
    }



    @Override
    public void dispose() {
        assetManager.dispose();
    }

    @Override
    public void error(AssetDescriptor asset, Throwable throwable) {

    }
}

assetManager.load(Constants.SKELETON_DATA_DIGGI,  SkeletonData.class);

exception in thread "LWJGL Application" com.badlogic.gdx.utils.GdxRuntimeException: No loader for type: SkeletonData