Example

function ExampleTab() {

    // 'getLabel()' returns the name of inventory tab.
    this.getLabel = function () {
        return "ExampleTab";
    };

    // 'getTabIconItem()' returns the item icon which should be used for the tab.
    this.getTabIconItem = function () {
        return Java.type("net.minecraft.init.Items").apple;
    };

    /* Inside 'displayAllReleventItems()' items can be added to the inventory. Make sure to properly 
    escape MetaData strings. The 'items' argument contains the items which have already been added 
    the inventory. */
    this.displayAllReleventItems = function (items) {
        items.add(item.createItem("dirt"));
        items.add(item.createItem("skull 1 3 {display:{Name:\"Chimney\"},SkullOwner:{Id:\"2a0069a3-30a6-4aa6-b0ae-d31f1bd777f3\",Properties:{textures:[{Value:\"eyJ0ZXh0dXJlcyI6eyJTS0lOIjp7InVybCI6Imh0dHA6Ly90ZXh0dXJlcy5taW5lY3JhZnQubmV0L3RleHR1cmUvZjk5NTljYjk5YzY5ZjA3MzE2YWUxNGY4OWVlMjU0YTAwMzRkOTFkMThiMTZmMGM5NDBiOTNjZDUzMjUzNjQ1MSJ9fX0=\"}]}}}"))
    };
}