Android Firestore文档无法删除数组子级

Question

请找到附件我的文档的数组结构： Structure of my documents arry

我尝试使用此代码删除此条目，但不幸的是，它不起作用：

      Map<String, Object> docData = new HashMap<>();
            Map<String, Object> deleteObject = new HashMap<>();

            deleteObject.put("chatId", users.get(position).getChatId());
            deleteObject.put("contactId", users.get(position).getId());
            deleteObject.put("isGroup", users.get(position).isGroup());
            deleteObject.put("isRead", users.get(position).isRead());
            deleteObject.put("lastMsg", users.get(position).getLastMsg());
            deleteObject.put("lastMsgTs", users.get(position).getLastMsgTs());
            deleteObject.put("sentBy", users.get(position).getSentBy());
            deleteObject.put("active", false);
            docData.put("openChats", FieldValue.arrayUnion(deleteObject));

            db.collection("Users").document(FirebaseAuth.getInstance().getCurrentUser().getUid())
                    .set(docData, SetOptions.merge()).addOnSuccessListener(new OnSuccessListener<Void>() {
                @Override
                public void onSuccess(Void aVoid) {
                    Toast.makeText(mActivity, "deleted", Toast.LENGTH_LONG).show();

                }
            }).addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                    Toast.makeText(mActivity, "Unable to delete", Toast.LENGTH_LONG).show();

                }
            });

我看不到任何错误，也调用了onSuccess。有人知道我不使用数组位置就可以输入一个地图吗