如何在flutter Firebase UI中获取AuthResult以查找additionalUserInfo

import 'package:firebase_auth/firebase_auth.dart';

final FirebaseAuth _auth = FirebaseAuth.instance;

import 'package:firebase_auth/firebase_auth.dart';
import 'package:firebase_auth_ui/firebase_auth_ui.dart';
import 'package:firebase_auth_ui/providers.dart';

final FirebaseAuth _auth = FirebaseAuth.instance;

void startFirebaseUI() {
  FirebaseAuthUi.instance().launchAuth([AuthProvider.email()],
      tosUrl: '<YOUR_TOS_URL>',
      signInOptions: [
        AuthUiOptions(
          provider: AuthProvider.email(),
          signInConfig: SignInConfig(
            signInOption: SignInOption.password,
            requireDisplayName: false,
          ),
        ),
      ]).then((firebaseUser) {
    if (firebaseUser != null) {
      // 用户已成功登录
      // 获取AuthResult
      firebaseUser.getIdToken().then((idToken) {
        AuthResult authResult = AuthResult(
          user: firebaseUser,
          additionalUserInfo: AdditionalUserInfo(
            isNewUser: false,
            profile: null,
            providerId: firebaseUser.providerId,
            username: null,
          ),
          credential: null,
          operationType: null,
        );
        // 在这里处理AuthResult
        handleAuthResult(authResult);
      });
    } else {
      // 用户取消了登录
    }
  }).catchError((error) {
    // 处理错误
  });
}

void handleAuthResult(AuthResult authResult) {
  // 在这里处理AuthResult
  // 可以通过authResult.additionalUserInfo获取additionalUserInfo
}