anchor.diff:    'package:cloud_firestore_platform_interface/src/geo_point.dart#GeoPoint',
   );
   
  +class GlobalData {
  +  final classPrefixesForLibrary = <Object?, List<String>>{};
  +}
  +
   @immutable
  -class CollectionGenerator extends ParserGenerator<void, Data, Collection> {
  +class CollectionGenerator
  +    extends ParserGenerator<GlobalData, Data, Collection> {
     final _collectionTemplates = <Template<CollectionData>>[
       CollectionReferenceTemplate(),
       DocumentReferenceTemplate(),
  
positive.code: 
      final classPrefix = data.classPrefix;
  
      if (_classPrefixes[annotatedElementSource]?.contains(classPrefix) ??
          false) {
        throw InvalidGenerationSourceError(
          'Defined a collection with duplicate class prefix $classPrefix.'
  
negative.code:   }
  
    @override
    GlobalData parseGlobalData(LibraryElement library) => GlobalData();
  }
  
  extension on ClassElement {
  