SkinResources.java

    private final Map<ResourceLocation, Future<ResourceLocation>> inprogress = Maps.newHashMap();
    
    @Nullable
    public ResourceLocation getPlayerTexture(GameProfile profile, Type type) {
        if (type != Type.SKIN)
            // not supported
            return null;

        Skin skin = getSkin(profile);
        if (skin != null) {
            ResourceLocation res = skin.getTexture();
            if (res != null) {
                ListenableFuture<ResourceLocation> conv = this.inprogress.get(res);
                if (conv == null) {
                    // read and convert in a new thread
                    conv = executor.submit(new ImageLoader(res));
                    conv.addListener(() -> converted.put(res, conv.get()));
                    this.inprogress.put(res, conv);
                }
            }
            return converted.get(res);
        }
        return null;
    }