diff --git a/modules/openapi-generator/src/main/resources/dart2/api_client.mustache b/modules/openapi-generator/src/main/resources/dart2/api_client.mustache
index 167b6951e01..f3af060d514 100644
--- a/modules/openapi-generator/src/main/resources/dart2/api_client.mustache
+++ b/modules/openapi-generator/src/main/resources/dart2/api_client.mustache
@@ -84,7 +84,7 @@ class ApiClient {
       ? '?${urlEncodedQueryParams.join('&')}'
       : '';
 
-    final url = '$basePath$path$queryString';
+    final Uri uri = Uri.parse('$basePath$path$queryString');
 
     if (nullableContentType != null) {
       headerParams['Content-Type'] = nullableContentType;
@@ -96,7 +96,7 @@ class ApiClient {
         body is MultipartFile && (nullableContentType == null ||
         !nullableContentType.toLowerCase().startsWith('multipart/form-data'))
       ) {
-        final request = StreamedRequest(method, Uri.parse(url));
+        final request = StreamedRequest(method, uri);
         request.headers.addAll(headerParams);
         request.contentLength = body.length;
         body.finalize().listen(
@@ -110,7 +110,7 @@ class ApiClient {
       }
 
       if (body is MultipartRequest) {
-        final request = MultipartRequest(method, Uri.parse(url));
+        final request = MultipartRequest(method, uri);
         request.fields.addAll(body.fields);
         request.files.addAll(body.files);
         request.headers.addAll(body.headers);
@@ -125,12 +125,12 @@ class ApiClient {
       final nullableHeaderParams = headerParams.isEmpty ? null : headerParams;
 
       switch(method) {
-        case 'POST': return await _client.post(url, headers: nullableHeaderParams, body: msgBody,);
-        case 'PUT': return await _client.put(url, headers: nullableHeaderParams, body: msgBody,);
-        case 'DELETE': return await _client.delete(url, headers: nullableHeaderParams,);
-        case 'PATCH': return await _client.patch(url, headers: nullableHeaderParams, body: msgBody,);
-        case 'HEAD': return await _client.head(url, headers: nullableHeaderParams,);
-        case 'GET': return await _client.get(url, headers: nullableHeaderParams,);
+        case 'POST': return await _client.post(uri, headers: nullableHeaderParams, body: msgBody,);
+        case 'PUT': return await _client.put(uri, headers: nullableHeaderParams, body: msgBody,);
+        case 'DELETE': return await _client.delete(uri, headers: nullableHeaderParams,);
+        case 'PATCH': return await _client.patch(uri, headers: nullableHeaderParams, body: msgBody,);
+        case 'HEAD': return await _client.head(uri, headers: nullableHeaderParams,);
+        case 'GET': return await _client.get(uri, headers: nullableHeaderParams,);
       }
     } on SocketException catch (e, trace) {
       throw ApiException.withInner(HttpStatus.badRequest, 'Socket operation failed: $method $path', e, trace,);
diff --git a/modules/openapi-generator/src/main/resources/dart2/build.yaml.mustache b/modules/openapi-generator/src/main/resources/dart2/build.yaml.mustache
index b5399b955db..89a4dd6e1c2 100644
--- a/modules/openapi-generator/src/main/resources/dart2/build.yaml.mustache
+++ b/modules/openapi-generator/src/main/resources/dart2/build.yaml.mustache
@@ -16,4 +16,3 @@ targets:
           field_rename: none
           ignore_unannotated: false
           include_if_null: false
-          nullable: true
diff --git a/modules/openapi-generator/src/main/resources/dart2/pubspec.mustache b/modules/openapi-generator/src/main/resources/dart2/pubspec.mustache
index 9de3cbd2314..93c848aa5c1 100644
--- a/modules/openapi-generator/src/main/resources/dart2/pubspec.mustache
+++ b/modules/openapi-generator/src/main/resources/dart2/pubspec.mustache
@@ -9,15 +9,15 @@ authors:
   - '{{{pubAuthor}}} <{{{pubAuthorEmail}}}>'
 homepage: '{{{pubHomepage}}}'
 environment:
-  sdk: '>=2.0.0 <3.0.0'
+  sdk: '>=2.12.0 <3.0.0'
 dependencies:
-  http: '>=0.12.0 <0.13.0'
-  intl: '^0.16.1'
+  http: '>=0.13.0 <0.14.0'
+  intl: '^0.17.0'
   meta: '^1.1.8'
 {{#json_serializable}}
   json_annotation: '^3.1.1'{{/json_serializable}}
 dev_dependencies:
-  test: '>=1.3.0 <1.16.0'
+  test: '>=1.16.0 <1.18.0'
 {{#json_serializable}}
-  build_runner: '^1.0.0'
+  build_runner: '^1.10.9'
   json_serializable: '^3.5.1'{{/json_serializable}}
diff --git a/samples/openapi3/client/petstore/dart2/petstore_client_lib/lib/api_client.dart b/samples/openapi3/client/petstore/dart2/petstore_client_lib/lib/api_client.dart
index c847d27f60b..35b984b86a1 100644
--- a/samples/openapi3/client/petstore/dart2/petstore_client_lib/lib/api_client.dart
+++ b/samples/openapi3/client/petstore/dart2/petstore_client_lib/lib/api_client.dart
@@ -77,7 +77,7 @@ class ApiClient {
       ? '?${urlEncodedQueryParams.join('&')}'
       : '';
 
-    final url = '$basePath$path$queryString';
+    final Uri uri = Uri.parse('$basePath$path$queryString');
 
     if (nullableContentType != null) {
       headerParams['Content-Type'] = nullableContentType;
@@ -89,7 +89,7 @@ class ApiClient {
         body is MultipartFile && (nullableContentType == null ||
         !nullableContentType.toLowerCase().startsWith('multipart/form-data'))
       ) {
-        final request = StreamedRequest(method, Uri.parse(url));
+        final request = StreamedRequest(method, uri);
         request.headers.addAll(headerParams);
         request.contentLength = body.length;
         body.finalize().listen(
@@ -103,7 +103,7 @@ class ApiClient {
       }
 
       if (body is MultipartRequest) {
-        final request = MultipartRequest(method, Uri.parse(url));
+        final request = MultipartRequest(method, uri);
         request.fields.addAll(body.fields);
         request.files.addAll(body.files);
         request.headers.addAll(body.headers);
@@ -118,12 +118,12 @@ class ApiClient {
       final nullableHeaderParams = headerParams.isEmpty ? null : headerParams;
 
       switch(method) {
-        case 'POST': return await _client.post(url, headers: nullableHeaderParams, body: msgBody,);
-        case 'PUT': return await _client.put(url, headers: nullableHeaderParams, body: msgBody,);
-        case 'DELETE': return await _client.delete(url, headers: nullableHeaderParams,);
-        case 'PATCH': return await _client.patch(url, headers: nullableHeaderParams, body: msgBody,);
-        case 'HEAD': return await _client.head(url, headers: nullableHeaderParams,);
-        case 'GET': return await _client.get(url, headers: nullableHeaderParams,);
+        case 'POST': return await _client.post(uri, headers: nullableHeaderParams, body: msgBody,);
+        case 'PUT': return await _client.put(uri, headers: nullableHeaderParams, body: msgBody,);
+        case 'DELETE': return await _client.delete(uri, headers: nullableHeaderParams,);
+        case 'PATCH': return await _client.patch(uri, headers: nullableHeaderParams, body: msgBody,);
+        case 'HEAD': return await _client.head(uri, headers: nullableHeaderParams,);
+        case 'GET': return await _client.get(uri, headers: nullableHeaderParams,);
       }
     } on SocketException catch (e, trace) {
       throw ApiException.withInner(HttpStatus.badRequest, 'Socket operation failed: $method $path', e, trace,);
diff --git a/samples/openapi3/client/petstore/dart2/petstore_client_lib/pubspec.yaml b/samples/openapi3/client/petstore/dart2/petstore_client_lib/pubspec.yaml
index 06e77263172..4d55880cd85 100644
--- a/samples/openapi3/client/petstore/dart2/petstore_client_lib/pubspec.yaml
+++ b/samples/openapi3/client/petstore/dart2/petstore_client_lib/pubspec.yaml
@@ -9,12 +9,12 @@ authors:
   - 'Author <author@homepage>'
 homepage: 'homepage'
 environment:
-  sdk: '>=2.0.0 <3.0.0'
+  sdk: '>=2.12.0 <3.0.0'
 dependencies:
-  http: '>=0.12.0 <0.13.0'
-  intl: '^0.16.1'
+  http: '>=0.13.0 <0.14.0'
+  intl: '^0.17.0'
   meta: '^1.1.8'
 
 dev_dependencies:
-  test: '>=1.3.0 <1.16.0'
+  test: '>=1.16.0 <1.18.0'
 
diff --git a/samples/openapi3/client/petstore/dart2/petstore_client_lib_fake/lib/api_client.dart b/samples/openapi3/client/petstore/dart2/petstore_client_lib_fake/lib/api_client.dart
index 83cad2d3ded..0aa83cf0197 100644
--- a/samples/openapi3/client/petstore/dart2/petstore_client_lib_fake/lib/api_client.dart
+++ b/samples/openapi3/client/petstore/dart2/petstore_client_lib_fake/lib/api_client.dart
@@ -80,7 +80,7 @@ class ApiClient {
       ? '?${urlEncodedQueryParams.join('&')}'
       : '';
 
-    final url = '$basePath$path$queryString';
+    final Uri uri = Uri.parse('$basePath$path$queryString');
 
     if (nullableContentType != null) {
       headerParams['Content-Type'] = nullableContentType;
@@ -92,7 +92,7 @@ class ApiClient {
         body is MultipartFile && (nullableContentType == null ||
         !nullableContentType.toLowerCase().startsWith('multipart/form-data'))
       ) {
-        final request = StreamedRequest(method, Uri.parse(url));
+        final request = StreamedRequest(method, uri);
         request.headers.addAll(headerParams);
         request.contentLength = body.length;
         body.finalize().listen(
@@ -106,7 +106,7 @@ class ApiClient {
       }
 
       if (body is MultipartRequest) {
-        final request = MultipartRequest(method, Uri.parse(url));
+        final request = MultipartRequest(method, uri);
         request.fields.addAll(body.fields);
         request.files.addAll(body.files);
         request.headers.addAll(body.headers);
@@ -121,12 +121,12 @@ class ApiClient {
       final nullableHeaderParams = headerParams.isEmpty ? null : headerParams;
 
       switch(method) {
-        case 'POST': return await _client.post(url, headers: nullableHeaderParams, body: msgBody,);
-        case 'PUT': return await _client.put(url, headers: nullableHeaderParams, body: msgBody,);
-        case 'DELETE': return await _client.delete(url, headers: nullableHeaderParams,);
-        case 'PATCH': return await _client.patch(url, headers: nullableHeaderParams, body: msgBody,);
-        case 'HEAD': return await _client.head(url, headers: nullableHeaderParams,);
-        case 'GET': return await _client.get(url, headers: nullableHeaderParams,);
+        case 'POST': return await _client.post(uri, headers: nullableHeaderParams, body: msgBody,);
+        case 'PUT': return await _client.put(uri, headers: nullableHeaderParams, body: msgBody,);
+        case 'DELETE': return await _client.delete(uri, headers: nullableHeaderParams,);
+        case 'PATCH': return await _client.patch(uri, headers: nullableHeaderParams, body: msgBody,);
+        case 'HEAD': return await _client.head(uri, headers: nullableHeaderParams,);
+        case 'GET': return await _client.get(uri, headers: nullableHeaderParams,);
       }
     } on SocketException catch (e, trace) {
       throw ApiException.withInner(HttpStatus.badRequest, 'Socket operation failed: $method $path', e, trace,);
diff --git a/samples/openapi3/client/petstore/dart2/petstore_client_lib_fake/pubspec.yaml b/samples/openapi3/client/petstore/dart2/petstore_client_lib_fake/pubspec.yaml
index 06e77263172..4d55880cd85 100644
--- a/samples/openapi3/client/petstore/dart2/petstore_client_lib_fake/pubspec.yaml
+++ b/samples/openapi3/client/petstore/dart2/petstore_client_lib_fake/pubspec.yaml
@@ -9,12 +9,12 @@ authors:
   - 'Author <author@homepage>'
 homepage: 'homepage'
 environment:
-  sdk: '>=2.0.0 <3.0.0'
+  sdk: '>=2.12.0 <3.0.0'
 dependencies:
-  http: '>=0.12.0 <0.13.0'
-  intl: '^0.16.1'
+  http: '>=0.13.0 <0.14.0'
+  intl: '^0.17.0'
   meta: '^1.1.8'
 
 dev_dependencies:
-  test: '>=1.3.0 <1.16.0'
+  test: '>=1.16.0 <1.18.0'
 
diff --git a/samples/openapi3/client/petstore/dart2/petstore_json_serializable_client_lib_fake/build.yaml b/samples/openapi3/client/petstore/dart2/petstore_json_serializable_client_lib_fake/build.yaml
index b5399b955db..89a4dd6e1c2 100644
--- a/samples/openapi3/client/petstore/dart2/petstore_json_serializable_client_lib_fake/build.yaml
+++ b/samples/openapi3/client/petstore/dart2/petstore_json_serializable_client_lib_fake/build.yaml
@@ -16,4 +16,3 @@ targets:
           field_rename: none
           ignore_unannotated: false
           include_if_null: false
-          nullable: true
diff --git a/samples/openapi3/client/petstore/dart2/petstore_json_serializable_client_lib_fake/lib/api_client.dart b/samples/openapi3/client/petstore/dart2/petstore_json_serializable_client_lib_fake/lib/api_client.dart
index f54d8cad38d..65c9ec57844 100644
--- a/samples/openapi3/client/petstore/dart2/petstore_json_serializable_client_lib_fake/lib/api_client.dart
+++ b/samples/openapi3/client/petstore/dart2/petstore_json_serializable_client_lib_fake/lib/api_client.dart
@@ -80,7 +80,7 @@ class ApiClient {
       ? '?${urlEncodedQueryParams.join('&')}'
       : '';
 
-    final url = '$basePath$path$queryString';
+    final Uri uri = Uri.parse('$basePath$path$queryString');
 
     if (nullableContentType != null) {
       headerParams['Content-Type'] = nullableContentType;
@@ -92,7 +92,7 @@ class ApiClient {
         body is MultipartFile && (nullableContentType == null ||
         !nullableContentType.toLowerCase().startsWith('multipart/form-data'))
       ) {
-        final request = StreamedRequest(method, Uri.parse(url));
+        final request = StreamedRequest(method, uri);
         request.headers.addAll(headerParams);
         request.contentLength = body.length;
         body.finalize().listen(
@@ -106,7 +106,7 @@ class ApiClient {
       }
 
       if (body is MultipartRequest) {
-        final request = MultipartRequest(method, Uri.parse(url));
+        final request = MultipartRequest(method, uri);
         request.fields.addAll(body.fields);
         request.files.addAll(body.files);
         request.headers.addAll(body.headers);
@@ -121,12 +121,12 @@ class ApiClient {
       final nullableHeaderParams = headerParams.isEmpty ? null : headerParams;
 
       switch(method) {
-        case 'POST': return await _client.post(url, headers: nullableHeaderParams, body: msgBody,);
-        case 'PUT': return await _client.put(url, headers: nullableHeaderParams, body: msgBody,);
-        case 'DELETE': return await _client.delete(url, headers: nullableHeaderParams,);
-        case 'PATCH': return await _client.patch(url, headers: nullableHeaderParams, body: msgBody,);
-        case 'HEAD': return await _client.head(url, headers: nullableHeaderParams,);
-        case 'GET': return await _client.get(url, headers: nullableHeaderParams,);
+        case 'POST': return await _client.post(uri, headers: nullableHeaderParams, body: msgBody,);
+        case 'PUT': return await _client.put(uri, headers: nullableHeaderParams, body: msgBody,);
+        case 'DELETE': return await _client.delete(uri, headers: nullableHeaderParams,);
+        case 'PATCH': return await _client.patch(uri, headers: nullableHeaderParams, body: msgBody,);
+        case 'HEAD': return await _client.head(uri, headers: nullableHeaderParams,);
+        case 'GET': return await _client.get(uri, headers: nullableHeaderParams,);
       }
     } on SocketException catch (e, trace) {
       throw ApiException.withInner(HttpStatus.badRequest, 'Socket operation failed: $method $path', e, trace,);
diff --git a/samples/openapi3/client/petstore/dart2/petstore_json_serializable_client_lib_fake/pubspec.yaml b/samples/openapi3/client/petstore/dart2/petstore_json_serializable_client_lib_fake/pubspec.yaml
index a54b8ac2006..73931cb6b83 100644
--- a/samples/openapi3/client/petstore/dart2/petstore_json_serializable_client_lib_fake/pubspec.yaml
+++ b/samples/openapi3/client/petstore/dart2/petstore_json_serializable_client_lib_fake/pubspec.yaml
@@ -9,13 +9,13 @@ authors:
   - 'Author <author@homepage>'
 homepage: 'homepage'
 environment:
-  sdk: '>=2.0.0 <3.0.0'
+  sdk: '>=2.12.0 <3.0.0'
 dependencies:
-  http: '>=0.12.0 <0.13.0'
-  intl: '^0.16.1'
+  http: '>=0.13.0 <0.14.0'
+  intl: '^0.17.0'
   meta: '^1.1.8'
   json_annotation: '^3.1.1'
 dev_dependencies:
-  test: '>=1.3.0 <1.16.0'
-  build_runner: '^1.0.0'
+  test: '>=1.16.0 <1.18.0'
+  build_runner: '^1.10.9'
   json_serializable: '^3.5.1'