GetLastSignedInAccount（）在发布版本时返回null

Question

        setContentView(R.layout.activity_login);
        SignInButton signInButton = findViewById(R.id.sign_in_button);
        signInButton.setSize(SignInButton.SIZE_WIDE);

        GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestIdToken(getString(R.string.default_web_client_id))
                .requestEmail()
                .build();
mGoogleSignInClient = GoogleSignIn.getClient(this, so);
}

    // Result returned from launching the Intent from GoogleSignInClient.getSignInIntent(...);
    if (requestCode == RC_SIGN_IN) {
        // The Task returned from this call is always completed, no need to attach
        // a listener.
        // Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
        Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
        try {
            // Google Sign In was successful, authenticate with Firebase
            GoogleSignInAccount account = task.getResult(ApiException.class);
            Log.e(TAG, "firebaseAuthWithGoogle:" + account.getId());
            //firebaseAuthWithGoogle(account.getIdToken());
        } catch (ApiException e) {
            // Google Sign In failed, update UI appropriately
            Log.e(TAG, "Google sign in failed", e);
        }
        handleSignInResult(task);
    }
}

 private void handleSignInResult(Task<GoogleSignInAccount> 
   completedTask) {
                String personName = "", personEmail = "", aid = "";
                 Uri personPhoto = Uri.parse("");
                // GoogleSignInAccount acct = 
    GoogleSignIn.getLastSignedInAccount(this);
                  GoogleSignInAccount acct = completedTask.getResult();
                  if (acct != null) {
                     personName = acct.getDisplayName();
                     personEmail = acct.getEmail();
                     personPhoto = acct.getPhotoUrl();
                     aid = acct.getId();
                     Log.e("ID_TOKEN", acct.getIdToken() + "");
                 } 
      }