Add an example of a global modification of an existing translation.

Author: ipcjs

example/lib/main.dart

@@ -1,3 +1,4 @@
+import 'package:example/override_form_builder_localizations_en.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_localizations/flutter_localizations.dart';
 import 'package:form_builder_validators/form_builder_validators.dart';
@@ -22,6 +23,7 @@ class MyApp extends StatelessWidget {
       ],
       localizationsDelegates: const [
         ...GlobalMaterialLocalizations.delegates,
+        OverrideFormBuilderLocalizationsEn.delegate,
         FormBuilderLocalizations.delegate,
       ],
     );

example/lib/override_form_builder_localizations_en.dart

@@ -0,0 +1,37 @@
+import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+import 'package:form_builder_validators/form_builder_validators.dart';
+
+/// Created by ipcjs on 2022/10/31.
+class OverrideFormBuilderLocalizationsEn
+    extends FormBuilderLocalizationsImplEn {
+  OverrideFormBuilderLocalizationsEn();
+
+  static const LocalizationsDelegate<FormBuilderLocalizationsImpl> delegate =
+      _LocalizationsDelegate();
+
+  static const List<Locale> supportedLocales = [Locale('en')];
+
+  @override
+  String get requiredErrorText => 'override: This field cannot be empty.';
+}
+
+class _LocalizationsDelegate
+    extends LocalizationsDelegate<FormBuilderLocalizationsImpl> {
+  const _LocalizationsDelegate();
+
+  @override
+  Future<FormBuilderLocalizationsImpl> load(Locale locale) {
+    final instance = OverrideFormBuilderLocalizationsEn();
+    // IMPORTANT!! must to invoke setCurrentInstance()
+    FormBuilderLocalizations.setCurrentInstance(instance);
+    return SynchronousFuture<FormBuilderLocalizationsImpl>(instance);
+  }
+
+  @override
+  bool isSupported(Locale locale) =>
+      OverrideFormBuilderLocalizationsEn.supportedLocales.contains(locale);
+
+  @override
+  bool shouldReload(_LocalizationsDelegate old) => false;
+}