Add cleanSubOutputDirectory allow clean up output directory before generating

openapi-generator-annotations/lib/src/openapi_generator_annotations_base.dart

@@ -50,6 +50,11 @@ class Openapi {
   ///  -o, --output
   final String? outputDirectory;
 
+  /// Defines whether the output directory should be cleaned up before generating the output.
+  /// 
+  /// e.g [''], ['lib/src']
+  final List<dynamic>? cleanSubOutputDirectory;
+
   /// Skips the default behavior of validating an input specification.
   ///
   /// --skip-validate-spec
@@ -118,6 +123,7 @@ class Openapi {
     this.templateDirectory,
     required this.generatorName,
     this.outputDirectory,
+    this.cleanSubOutputDirectory,
     this.typeMappings,
     this.importMappings,
     this.reservedWordsMappings,

openapi-generator/lib/src/extensions/type_methods.dart

@@ -172,7 +172,7 @@ extension ReadProperty on ConstantReader {
     } else if (isA(v, Set)) {
       return v.setValue.map(convertToPropertyValue) as T;
     } else if (isA(v, List)) {
-      return v.listValue.map(convertToPropertyValue) as T;
+      return v.listValue.map(convertToPropertyValue).toList() as T;
     } else if (isA(v, Enum)) {
       return v.enumValue();
     } else {

openapi-generator/lib/src/models/generator_arguments.dart

@@ -32,6 +32,9 @@ class GeneratorArguments {
   /// Default: Directory.current.path
   final String? outputDirectory;
 
+  /// Defines whether the output directory should be cleaned up before generating the output.
+  final List<dynamic>? cleanSubOutputDirectory;
+
   /// Informs the generator to run source gen on the output.
   ///
   /// Default: true
@@ -105,6 +108,8 @@ class GeneratorArguments {
         shouldFetchDependencies =
             annotations.readPropertyOrDefault('fetchDependencies', true),
         outputDirectory = annotations.readPropertyOrNull('outputDirectory'),
+        cleanSubOutputDirectory =
+            annotations.readPropertyOrNull('cleanSubOutputDirectory'),
         cachePath =
             annotations.readPropertyOrDefault('cachePath', defaultCachedPath),
         pubspecPath = annotations.readPropertyOrDefault<String>(

openapi-generator/lib/src/openapi_generator_runner.dart

@@ -90,6 +90,33 @@ class OpenapiGenerator extends GeneratorForAnnotation<annots.Openapi> {
       ),
     );
 
+    if (arguments.cleanSubOutputDirectory != null) {
+      arguments.cleanSubOutputDirectory?.forEach((directory) {
+        final childDirectory =
+            Directory('${arguments.outputDirectory}/${directory.toString()}');
+        try {
+          final outputDirectory = Directory('${arguments.outputDirectory}')
+              .resolveSymbolicLinksSync();
+          // Make sure is sub directory, avoid ../../
+          if (childDirectory
+              .resolveSymbolicLinksSync()
+              .startsWith(outputDirectory)) {
+            childDirectory.delete(recursive: true);
+          }
+        } catch (e, st) {
+          logOutputMessage(
+            log: log,
+            communication: OutputMessage(
+              message: 'Output directory already empty',
+              additionalContext: e,
+              stackTrace: st,
+              level: Level.WARNING,
+            ),
+          );
+        }
+      });
+    }
+
     var binPath = (await Isolate.resolvePackageUri(
             Uri.parse('package:openapi_generator_cli/openapi-generator.jar')))!
         .toFilePath(windows: Platform.isWindows);