anchor.diff:    Future<void> test_addSuggestions() async {
       var groupName = 'a';
       var builder = ChangeBuilderImpl();
  -    await builder.addFileEdit(path, (FileEditBuilder builder) {
  -      builder.addInsertion(10, (EditBuilder builder) {
  -        builder.addLinkedEdit(groupName, (LinkedEditBuilder builder) {
  +    await builder.addGenericFileEdit(path, (builder) {
  +      builder.addInsertion(10, (builder) {
  +        builder.addLinkedEdit(groupName, (builder) {
             builder.write('A');
             builder.addSuggestions(LinkedEditSuggestionKind.TYPE, ['B', 'C']);
           });
  
positive.code:     var builder = ChangeBuilderImpl();
      var offset = 10;
      var text = 'content';
      await builder.addFileEdit(path, (FileEditBuilder builder) {
        builder.addInsertion(10, (EditBuilder builder) {
          builder.addLinkedEdit('a', (LinkedEditBuilder builder) {
            builder.write(text);
          });
          var sourceEdit = (builder as EditBuilderImpl).sourceEdit;
  
negative.code:   Future<void> test_addLinkedPosition() async {
      var builder = ChangeBuilderImpl();
      var groupName = 'a';
      await builder.addGenericFileEdit(path, (builder) {
        builder.addLinkedPosition(SourceRange(3, 6), groupName);
      });
  
  