我的問題是從 firestore 獲取文檔 ID。我如何獲取 Users/documentid/Comments/documentid ？數據類：public class BlogPostId {  @Exclude  public String BlogPostId;  public <T extends BlogPostId> T withId(@NonNull final String id) {    this.BlogPostId = id;    return (T) this;  }}添加活動：private String blog_post_id;Oncreateblog_post_id = getIntent().getStringExtra("blog_post_id");btn clickfinal String descff = icerikedit.getText().toString();Map<String, Object> commentsMap = new HashMap<>();            commentsMap.put("descff", descff);            commentsMap.put("user_id", current_user_id);            commentsMap.put("timestamp", FieldValue.serverTimestamp());            firebaseFirestore.collection("Users/"+blog_post_id+"/Comments").add(commentsMap).addOnCompleteListener(new OnCompleteListener<DocumentReference>() {    @Override    public void onComplete(@NonNull Task<DocumentReference> task) {        if(task.isSuccessful()){            Toast.makeText(FFicerikAdd.this, "Ba?ar?l? efe!", Toast.LENGTH_SHORT).show();            Intent sab=new Intent(getApplicationContext(),FFicerik.class);            sab.putExtra("blog_post_id",blog_post_id);            startActivity(sab);        }