FireStore anyQuery.onComplete（） 将始终在主线程上运行？这很奇怪

问：

class ExampleThread extends  Thread {
        @Override
        public void run() {
            Log.d(TAG, "ExampleThread->run: currentThread= " + Thread.currentThread().getId());
            db.collection("PointsAndRating")
                    .orderBy("gmq", Query.Direction.DESCENDING)
                    .get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                @Override
                public void onComplete(@NonNull Task<QuerySnapshot> task) {
                    for (QueryDocumentSnapshot document : task.getResult()) {
                        Log.d(TAG, "ExampleThread->run: currentThread= " + Thread.currentThread().getId());
                        Log.d(TAG, document.getId() + "=accumulatedUpdatedNugget=@@ => " + document.getData());
                    } // end of for loop
                }
            });
        }
    } // end of ExampleThread

不幸的是，行返回 1。Log.d(TAG, "ExampleThread->run: currentThread= " + Thread.currentThread().getId());