如何在Android Firestore中等待嵌套任务？

Question

我有以下方法：

    public static void getRecipe(DocumentReference DR){
        Recipe r = new Recipe();

        /*First Firestore Query! - Get the recipe*/
        DR.get().addOnCompleteListener(task -> {
                if (task.isSuccessful() && task.getResult() != null) {

                    r.addStuff(...);
                    r.addMoreStuff(...);
                    r.addEvenMoreStuff(...);   
              
                    /*Second Firestore Query(s)! - Get the ingredient(s)*/
                    for(DocumentReference DR_ingredient : ingredients) {
                        Task<DocumentSnapshot> IngredientQuery = DR_ingredient.get();

                        IngredientQuery.addOnCompleteListener(t -> {
                                    if (t.isSuccessful() && t.getResult() != null) {                                      
                                         /*even more stuff*/
                                    }
                        });
                    }


                    //After all tasks are finished, we can finally put the recipe in our Database!
                    Task<Void> t = Tasks.whenAll(IngredientQueries);
                    t.addOnSuccessListener(unused -> {
                        addRecipe(r);
                    });
                 
                }
           });
}

该方法使用Firestore来获取保存的食谱，并进一步加载所选食谱的配料。这些成分将保存为配方中的参考，并且必须根据Firebase重新加载。

我现在的问题是：如果我从另一个类中调用getRecipe(DocumentReference DR)，我如何才能等到所有内容加载完毕然后继续执行我的代码？