cloud_firestore_mocks failure upon FieldValue.serverTimestamp() and FieldValue.delete()

mock_firestore_test.dart

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:cloud_firestore_mocks/cloud_firestore_mocks.dart';
import 'package:flutter_test/flutter_test.dart';


void main() {
  testWidgets('FieldValue.serverTimestamp does not work',
      (WidgetTester tester) async {
    final fakeFirestore = MockFirestoreInstance();

    // Application initial status. 2 users Bob (aaabbcc) and irrelevantUserId
    final subcollectionRef = fakeFirestore
        .collection('users')
        .document('qwpeoivjkasdu')
        .collection('notes');
    await subcollectionRef.document('foobar')
        .setData(<String, dynamic>{
      'content': 'MockFirestoreInstance is great',
      'createdBy': 'Tomo', 
//      'created': FieldValue.serverTimestamp(), // type 'MethodChannelFieldValue' is not a subtype of type 'MockFieldValuePlatform' in type cast
    });

    await subcollectionRef.document('foobar')
        .setData(<String, dynamic>{
      'content': FieldValue.delete() // type 'MethodChannelFieldValue' is not a subtype of type 'MockFieldValuePlatform' in type cast
    });
        
    final retrievedNotes = await subcollectionRef.getDocuments();
    for (final snapshot in retrievedNotes.documents) {
      expect(snapshot['content'], 'MockFirestoreInstance is great');
    }
  });
}