diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartClientCodegen.java
index 7b5654c7279..a45bac4fd2c 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartClientCodegen.java
@@ -21,23 +21,17 @@ import java.io.BufferedReader;
 import java.io.File;
 import java.io.InputStreamReader;
 import java.nio.charset.StandardCharsets;
-import java.util.ArrayList;
-import java.util.EnumSet;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
+import java.util.*;
 
 import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
 
+import io.swagger.v3.oas.models.Operation;
+import io.swagger.v3.oas.models.media.StringSchema;
+import io.swagger.v3.oas.models.servers.Server;
 import org.apache.commons.io.FilenameUtils;
 import org.apache.commons.lang3.StringUtils;
-import org.openapitools.codegen.CliOption;
-import org.openapitools.codegen.CodegenConstants;
-import org.openapitools.codegen.CodegenType;
-import org.openapitools.codegen.DefaultCodegen;
-import org.openapitools.codegen.SupportingFile;
+import org.openapitools.codegen.*;
 import org.openapitools.codegen.meta.features.ClientModificationFeature;
 import org.openapitools.codegen.meta.features.DocumentationFeature;
 import org.openapitools.codegen.meta.features.GlobalFeature;
@@ -106,9 +100,6 @@ public class DartClientCodegen extends DefaultCodegen {
                 )
         );
 
-        // clear import mapping (from default generator) as dart does not use it at the moment
-        importMapping.clear();
-
         outputFolder = "generated-code/dart";
         modelTemplateFiles.put("model.mustache", ".dart");
         apiTemplateFiles.put("api.mustache", ".dart");
@@ -174,8 +165,6 @@ public class DartClientCodegen extends DefaultCodegen {
 
         // These are needed as they prevent models from being generated
         // which would clash with existing types, e.g. List
-        // Importing dart:core doesn't hurt but a subclass may choose to skip
-        // dart:core imports.
         importMapping.put("dynamic", "dart:core");
         importMapping.put("Object", "dart:core");
         importMapping.put("String", "dart:core");
@@ -188,6 +177,8 @@ public class DartClientCodegen extends DefaultCodegen {
         importMapping.put("Set", "dart:core");
         importMapping.put("DateTime", "dart:core");
 
+        defaultIncludes = new HashSet<>(Collections.singletonList("dart:core"));
+
         cliOptions.add(new CliOption(PUB_LIBRARY, "Library name in generated code"));
         cliOptions.add(new CliOption(PUB_NAME, "Name in generated pubspec"));
         cliOptions.add(new CliOption(PUB_VERSION, "Version in generated pubspec"));
@@ -474,27 +465,38 @@ public class DartClientCodegen extends DefaultCodegen {
 
     @Override
     public String getTypeDeclaration(Schema p) {
-        if (ModelUtils.isArraySchema(p)) {
-            ArraySchema ap = (ArraySchema) p;
-            Schema inner = ap.getItems();
-            return instantiationTypes().get("array") + "<" + getTypeDeclaration(inner) + ">";
-        } else if (ModelUtils.isMapSchema(p)) {
-            Schema inner = getAdditionalProperties(p);
-            return instantiationTypes().get("map") + "<String, " + getTypeDeclaration(inner) + ">";
+        Schema<?> schema = ModelUtils.unaliasSchema(this.openAPI, p, importMapping);
+        Schema<?> target = ModelUtils.isGenerateAliasAsModel() ? p : schema;
+        if (ModelUtils.isArraySchema(target)) {
+            Schema<?> items = getSchemaItems((ArraySchema) schema);
+            return getSchemaType(target) + "<" + getTypeDeclaration(items) + ">";
+        } else if (ModelUtils.isMapSchema(target)) {
+            // Note: ModelUtils.isMapSchema(p) returns true when p is a composed schema that also defines
+            // additionalproperties: true
+            Schema<?> inner = getAdditionalProperties(target);
+            if (inner == null) {
+                LOGGER.error("`{}` (map property) does not have a proper inner type defined. Default to type:string", p.getName());
+                inner = new StringSchema().description("TODO default missing map inner type to string");
+                p.setAdditionalProperties(inner);
+            }
+            return getSchemaType(target) + "<String, " + getTypeDeclaration(inner) + ">";
         }
         return super.getTypeDeclaration(p);
     }
 
     @Override
     public String getSchemaType(Schema p) {
-        String type = super.getSchemaType(p);
-        if (typeMapping.containsKey(type)) {
-            return typeMapping.get(type);
+        String openAPIType = super.getSchemaType(p);
+        if (openAPIType == null) {
+            LOGGER.error("No Type defined for Schema " + p);
         }
-        if (languageSpecificPrimitives.contains(type)) {
-            return type;
+        if (typeMapping.containsKey(openAPIType)) {
+            return typeMapping.get(openAPIType);
         }
-        return toModelName(type);
+        if (languageSpecificPrimitives.contains(openAPIType)) {
+            return openAPIType;
+        }
+        return toModelName(openAPIType);
     }
 
     @Override
@@ -502,6 +504,23 @@ public class DartClientCodegen extends DefaultCodegen {
         return postProcessModelsEnum(objs);
     }
 
+    @Override
+    public CodegenOperation fromOperation(String path, String httpMethod, Operation operation, List<Server> servers) {
+        final CodegenOperation op = super.fromOperation(path, httpMethod, operation, servers);
+        for (CodegenResponse r : op.responses) {
+            // By default only set types are automatically added to operation imports, not sure why.
+            // Add all container type imports here, by default 'dart:core' imports are skipped
+            // but other sub classes may required specific container type imports.
+            if (r.containerType != null && typeMapping().containsKey(r.containerType)) {
+                final String value = typeMapping().get(r.containerType);
+                if (needToImport(value)) {
+                    op.imports.add(value);
+                }
+            }
+        }
+        return op;
+    }
+
     @Override
     protected void updateEnumVarsWithExtensions(List<Map<String, Object>> enumVars, Map<String, Object> vendorExtensions, String dataType) {
         if (vendorExtensions != null && useEnumExtension && vendorExtensions.containsKey("x-enum-values")) {
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartDioClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartDioClientCodegen.java
index 16cc7107139..0a400b9da13 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartDioClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartDioClientCodegen.java
@@ -37,7 +37,6 @@ import java.util.*;
 
 import io.swagger.v3.oas.models.media.Schema;
 
-import static org.openapitools.codegen.utils.StringUtils.camelize;
 import static org.openapitools.codegen.utils.StringUtils.underscore;
 
 public class DartDioClientCodegen extends DartClientCodegen {
@@ -67,9 +66,15 @@ public class DartDioClientCodegen extends DartClientCodegen {
         dateLibrary.setEnum(dateOptions);
         cliOptions.add(dateLibrary);
 
+        typeMapping.put("Array", "BuiltList");
+        typeMapping.put("array", "BuiltList");
+        typeMapping.put("List", "BuiltList");
+        typeMapping.put("set", "BuiltSet");
+        typeMapping.put("map", "BuiltMap");
         typeMapping.put("file", "Uint8List");
         typeMapping.put("binary", "Uint8List");
-        typeMapping.put("AnyType", "Object");
+        typeMapping.put("object", "JsonObject");
+        typeMapping.put("AnyType", "JsonObject");
 
         importMapping.put("BuiltList", "package:built_collection/built_collection.dart");
         importMapping.put("BuiltSet", "package:built_collection/built_collection.dart");
@@ -261,7 +266,7 @@ public class DartDioClientCodegen extends DartClientCodegen {
             for (String modelImport : cm.imports) {
                 if (importMapping().containsKey(modelImport)) {
                     final String value = importMapping().get(modelImport);
-                    if (!Objects.equals(value, "dart:core")) {
+                    if (needToImport(value)) {
                         modelImports.add(value);
                     }
                 } else {
@@ -278,31 +283,11 @@ public class DartDioClientCodegen extends DartClientCodegen {
 
     @Override
     public void postProcessModelProperty(CodegenModel model, CodegenProperty property) {
+        super.postProcessModelProperty(model, property);
         if (nullableFields) {
             property.isNullable = true;
         }
 
-        property.setDatatype(property.getDataType()
-                .replaceAll("\\bList\\b", "BuiltList")
-                .replaceAll("\\bMap\\b", "BuiltMap")
-                .replaceAll("\\bObject\\b", "JsonObject")
-        );
-        property.setBaseType(property.getBaseType()
-                .replaceAll("\\bList\\b", "BuiltList")
-                .replaceAll("\\bMap\\b", "BuiltMap")
-                .replaceAll("\\bObject\\b", "JsonObject")
-        );
-
-        if (property.dataType.contains("BuiltList")) {
-            model.imports.add("BuiltList");
-        }
-        if (property.dataType.contains("BuiltMap")) {
-            model.imports.add("BuiltMap");
-        }
-        if (property.dataType.contains("JsonObject")) {
-            model.imports.add("JsonObject");
-        }
-
         if (property.isEnum) {
             // enums are generated with built_value and make use of BuiltSet
             model.imports.add("BuiltSet");
@@ -354,7 +339,7 @@ public class DartDioClientCodegen extends DartClientCodegen {
             for (String item : op.imports) {
                 if (importMapping().containsKey(item)) {
                     final String value = importMapping().get(item);
-                    if (!Objects.equals(value, "dart:core")) {
+                    if (needToImport(value)) {
                         fullImports.add(value);
                     }
                 } else {
diff --git a/modules/openapi-generator/src/main/resources/dart-dio/api.mustache b/modules/openapi-generator/src/main/resources/dart-dio/api.mustache
index 6758f93825d..884dfb2fe56 100644
--- a/modules/openapi-generator/src/main/resources/dart-dio/api.mustache
+++ b/modules/openapi-generator/src/main/resources/dart-dio/api.mustache
@@ -2,7 +2,6 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:convert';
 import 'package:dio/dio.dart';
-import 'package:built_collection/built_collection.dart';
 import 'package:built_value/serializer.dart';
 
 {{#operations}}
@@ -64,13 +63,13 @@ class {{classname}} {
 
         {{#bodyParam}}
             {{#isArray}}
-            final type = const FullType(BuiltList, const [const FullType({{baseType}})]);
-            var serializedBody = _serializers.serialize(BuiltList<{{baseType}}>.from({{paramName}}), specifiedType: type);
+            const type = FullType(BuiltList, [FullType({{baseType}})]);
+            final serializedBody = _serializers.serialize({{paramName}}, specifiedType: type);
             {{/isArray}}
             {{^isArray}}
-            var serializedBody = _serializers.serialize({{paramName}});
+            final serializedBody = _serializers.serialize({{paramName}});
             {{/isArray}}
-            var json{{paramName}} = json.encode(serializedBody);
+            final json{{paramName}} = json.encode(serializedBody);
             bodyData = json{{paramName}};
         {{/bodyParam}}
 
@@ -94,30 +93,25 @@ class {{classname}} {
             onReceiveProgress: onReceiveProgress,
             ){{#returnType}}.then((response) {
 
-        {{#returnTypeIsPrimitive}}
-            var data = response.data as {{{returnType}}};
-        {{/returnTypeIsPrimitive}}
-        {{^returnTypeIsPrimitive}}
         {{#isResponseFile}}
             final data = response.data;
         {{/isResponseFile}}
         {{^isResponseFile}}
-        {{#isArray}}
-            final FullType type = const FullType(BuiltList, const [const FullType({{returnBaseType}})]);
-            final BuiltList<{{returnBaseType}}> dataList = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
-            final data = dataList.toList();
-        {{/isArray}}
-        {{^isArray}}
-        {{#isMap}}
-            final serializer = _serializers.serializerForType(Map);
-        {{/isMap}}
-        {{^isMap}}
-            final serializer = _serializers.serializerForType({{{returnType}}});
-        {{/isMap}}
-            final data = _serializers.deserializeWith<{{{returnType}}}>(serializer, response.data is String ? jsonDecode(response.data) : response.data);
-        {{/isArray}}
-        {{/isResponseFile}}
+        {{#returnSimpleType}}
+        {{#returnTypeIsPrimitive}}
+            final data = response.data as {{{returnType}}};
         {{/returnTypeIsPrimitive}}
+        {{^returnTypeIsPrimitive}}
+            final serializer = _serializers.serializerForType({{{returnType}}});
+            final data = _serializers.deserializeWith<{{{returnType}}}>(serializer, response.data is String ? jsonDecode(response.data) : response.data);
+        {{/returnTypeIsPrimitive}}
+        {{/returnSimpleType}}
+        {{^returnSimpleType}}
+            const collectionType = {{#isMap}}BuiltMap{{/isMap}}{{^isMap}}BuiltList{{/isMap}};
+            const type = FullType(collectionType, [{{#isMap}}FullType(String), {{/isMap}}FullType({{{returnBaseType}}})]);
+            final {{{returnType}}} data = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
+        {{/returnSimpleType}}
+        {{/isResponseFile}}
 
             return Response<{{{returnType}}}>(
                 data: data,
diff --git a/samples/client/petstore/dart-dio/petstore_client_lib/doc/PetApi.md b/samples/client/petstore/dart-dio/petstore_client_lib/doc/PetApi.md
index e781974607c..47f6cef7a2d 100644
--- a/samples/client/petstore/dart-dio/petstore_client_lib/doc/PetApi.md
+++ b/samples/client/petstore/dart-dio/petstore_client_lib/doc/PetApi.md
@@ -106,7 +106,7 @@ void (empty response body)
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
 # **findPetsByStatus**
-> List<Pet> findPetsByStatus(status)
+> BuiltList<Pet> findPetsByStatus(status)
 
 Finds Pets by status
 
@@ -119,7 +119,7 @@ import 'package:openapi/api.dart';
 //defaultApiClient.getAuthentication<OAuth>('petstore_auth').accessToken = 'YOUR_ACCESS_TOKEN';
 
 var api_instance = new PetApi();
-var status = []; // List<String> | Status values that need to be considered for filter
+var status = []; // BuiltList<String> | Status values that need to be considered for filter
 
 try { 
     var result = api_instance.findPetsByStatus(status);
@@ -133,11 +133,11 @@ try {
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **status** | [**List&lt;String&gt;**](String.md)| Status values that need to be considered for filter | [default to const []]
+ **status** | [**BuiltList&lt;String&gt;**](String.md)| Status values that need to be considered for filter | [default to const []]
 
 ### Return type
 
-[**List<Pet>**](Pet.md)
+[**BuiltList<Pet>**](Pet.md)
 
 ### Authorization
 
@@ -151,7 +151,7 @@ Name | Type | Description  | Notes
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
 # **findPetsByTags**
-> List<Pet> findPetsByTags(tags)
+> BuiltList<Pet> findPetsByTags(tags)
 
 Finds Pets by tags
 
@@ -164,7 +164,7 @@ import 'package:openapi/api.dart';
 //defaultApiClient.getAuthentication<OAuth>('petstore_auth').accessToken = 'YOUR_ACCESS_TOKEN';
 
 var api_instance = new PetApi();
-var tags = []; // List<String> | Tags to filter by
+var tags = []; // BuiltList<String> | Tags to filter by
 
 try { 
     var result = api_instance.findPetsByTags(tags);
@@ -178,11 +178,11 @@ try {
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **tags** | [**List&lt;String&gt;**](String.md)| Tags to filter by | [default to const []]
+ **tags** | [**BuiltList&lt;String&gt;**](String.md)| Tags to filter by | [default to const []]
 
 ### Return type
 
-[**List<Pet>**](Pet.md)
+[**BuiltList<Pet>**](Pet.md)
 
 ### Authorization
 
diff --git a/samples/client/petstore/dart-dio/petstore_client_lib/doc/StoreApi.md b/samples/client/petstore/dart-dio/petstore_client_lib/doc/StoreApi.md
index 33896baac9b..fac1bb187aa 100644
--- a/samples/client/petstore/dart-dio/petstore_client_lib/doc/StoreApi.md
+++ b/samples/client/petstore/dart-dio/petstore_client_lib/doc/StoreApi.md
@@ -58,7 +58,7 @@ No authorization required
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
 # **getInventory**
-> Map<String, int> getInventory()
+> BuiltMap<String, int> getInventory()
 
 Returns pet inventories by status
 
@@ -87,7 +87,7 @@ This endpoint does not need any parameter.
 
 ### Return type
 
-**Map<String, int>**
+**BuiltMap<String, int>**
 
 ### Authorization
 
diff --git a/samples/client/petstore/dart-dio/petstore_client_lib/doc/UserApi.md b/samples/client/petstore/dart-dio/petstore_client_lib/doc/UserApi.md
index 052dc20aef7..de14cb998df 100644
--- a/samples/client/petstore/dart-dio/petstore_client_lib/doc/UserApi.md
+++ b/samples/client/petstore/dart-dio/petstore_client_lib/doc/UserApi.md
@@ -71,7 +71,7 @@ Creates list of users with given input array
 import 'package:openapi/api.dart';
 
 var api_instance = new UserApi();
-var body = [new List&lt;User&gt;()]; // List<User> | List of user object
+var body = [new BuiltList&lt;User&gt;()]; // BuiltList<User> | List of user object
 
 try { 
     api_instance.createUsersWithArrayInput(body);
@@ -84,7 +84,7 @@ try {
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **body** | [**List&lt;User&gt;**](User.md)| List of user object | 
+ **body** | [**BuiltList&lt;User&gt;**](User.md)| List of user object | 
 
 ### Return type
 
@@ -111,7 +111,7 @@ Creates list of users with given input array
 import 'package:openapi/api.dart';
 
 var api_instance = new UserApi();
-var body = [new List&lt;User&gt;()]; // List<User> | List of user object
+var body = [new BuiltList&lt;User&gt;()]; // BuiltList<User> | List of user object
 
 try { 
     api_instance.createUsersWithListInput(body);
@@ -124,7 +124,7 @@ try {
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **body** | [**List&lt;User&gt;**](User.md)| List of user object | 
+ **body** | [**BuiltList&lt;User&gt;**](User.md)| List of user object | 
 
 ### Return type
 
diff --git a/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart b/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart
index aa095015f5a..5d3e4e37ac6 100644
--- a/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart
+++ b/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart
@@ -2,12 +2,12 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:convert';
 import 'package:dio/dio.dart';
-import 'package:built_collection/built_collection.dart';
 import 'package:built_value/serializer.dart';
 
 import 'package:openapi/model/pet.dart';
 import 'package:openapi/model/api_response.dart';
 import 'dart:typed_data';
+import 'package:built_collection/built_collection.dart';
 import 'package:openapi/api_util.dart';
 
 class PetApi {
@@ -33,8 +33,8 @@ class PetApi {
         List<String> contentTypes = ["application/json","application/xml"];
 
 
-            var serializedBody = _serializers.serialize(body);
-            var jsonbody = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(body);
+            final jsonbody = json.encode(serializedBody);
             bodyData = jsonbody;
 
             return _dio.request(
@@ -93,7 +93,7 @@ class PetApi {
         /// Finds Pets by status
         ///
         /// Multiple status values can be provided with comma separated strings
-        Future<Response<List<Pet>>>findPetsByStatus(List<String> status,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response<BuiltList<Pet>>>findPetsByStatus(BuiltList<String> status,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/pet/findByStatus";
 
@@ -126,11 +126,11 @@ class PetApi {
             onReceiveProgress: onReceiveProgress,
             ).then((response) {
 
-            final FullType type = const FullType(BuiltList, const [const FullType(Pet)]);
-            final BuiltList<Pet> dataList = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
-            final data = dataList.toList();
+            const collectionType = BuiltList;
+            const type = FullType(collectionType, [FullType(Pet)]);
+            final BuiltList<Pet> data = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
 
-            return Response<List<Pet>>(
+            return Response<BuiltList<Pet>>(
                 data: data,
                 headers: response.headers,
                 request: response.request,
@@ -144,7 +144,7 @@ class PetApi {
         /// Finds Pets by tags
         ///
         /// Multiple tags can be provided with comma separated strings. Use tag1, tag2, tag3 for testing.
-        Future<Response<List<Pet>>>findPetsByTags(List<String> tags,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response<BuiltList<Pet>>>findPetsByTags(BuiltList<String> tags,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/pet/findByTags";
 
@@ -177,11 +177,11 @@ class PetApi {
             onReceiveProgress: onReceiveProgress,
             ).then((response) {
 
-            final FullType type = const FullType(BuiltList, const [const FullType(Pet)]);
-            final BuiltList<Pet> dataList = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
-            final data = dataList.toList();
+            const collectionType = BuiltList;
+            const type = FullType(collectionType, [FullType(Pet)]);
+            final BuiltList<Pet> data = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
 
-            return Response<List<Pet>>(
+            return Response<BuiltList<Pet>>(
                 data: data,
                 headers: response.headers,
                 request: response.request,
@@ -258,8 +258,8 @@ class PetApi {
         List<String> contentTypes = ["application/json","application/xml"];
 
 
-            var serializedBody = _serializers.serialize(body);
-            var jsonbody = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(body);
+            final jsonbody = json.encode(serializedBody);
             bodyData = jsonbody;
 
             return _dio.request(
diff --git a/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart b/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart
index 5aa5f69da51..d7ae685d211 100644
--- a/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart
+++ b/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart
@@ -2,10 +2,10 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:convert';
 import 'package:dio/dio.dart';
-import 'package:built_collection/built_collection.dart';
 import 'package:built_value/serializer.dart';
 
 import 'package:openapi/model/order.dart';
+import 'package:built_collection/built_collection.dart';
 
 class StoreApi {
     final Dio _dio;
@@ -51,7 +51,7 @@ class StoreApi {
         /// Returns pet inventories by status
         ///
         /// Returns a map of status codes to quantities
-        Future<Response<Map<String, int>>>getInventory({ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response<BuiltMap<String, int>>>getInventory({ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/store/inventory";
 
@@ -83,9 +83,11 @@ class StoreApi {
             onReceiveProgress: onReceiveProgress,
             ).then((response) {
 
-            var data = response.data as Map<String, int>;
+            const collectionType = BuiltMap;
+            const type = FullType(collectionType, [FullType(String), FullType(int)]);
+            final BuiltMap<String, int> data = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
 
-            return Response<Map<String, int>>(
+            return Response<BuiltMap<String, int>>(
                 data: data,
                 headers: response.headers,
                 request: response.request,
@@ -162,8 +164,8 @@ class StoreApi {
         List<String> contentTypes = [];
 
 
-            var serializedBody = _serializers.serialize(body);
-            var jsonbody = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(body);
+            final jsonbody = json.encode(serializedBody);
             bodyData = jsonbody;
 
             return _dio.request(
diff --git a/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart b/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart
index eb7a6b4bdde..20406454ed8 100644
--- a/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart
+++ b/samples/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart
@@ -2,10 +2,10 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:convert';
 import 'package:dio/dio.dart';
-import 'package:built_collection/built_collection.dart';
 import 'package:built_value/serializer.dart';
 
 import 'package:openapi/model/user.dart';
+import 'package:built_collection/built_collection.dart';
 
 class UserApi {
     final Dio _dio;
@@ -30,8 +30,8 @@ class UserApi {
         List<String> contentTypes = [];
 
 
-            var serializedBody = _serializers.serialize(body);
-            var jsonbody = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(body);
+            final jsonbody = json.encode(serializedBody);
             bodyData = jsonbody;
 
             return _dio.request(
@@ -54,7 +54,7 @@ class UserApi {
         /// Creates list of users with given input array
         ///
         /// 
-        Future<Response>createUsersWithArrayInput(List<User> body,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response>createUsersWithArrayInput(BuiltList<User> body,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/user/createWithArray";
 
@@ -68,9 +68,9 @@ class UserApi {
         List<String> contentTypes = [];
 
 
-            final type = const FullType(BuiltList, const [const FullType(User)]);
-            var serializedBody = _serializers.serialize(BuiltList<User>.from(body), specifiedType: type);
-            var jsonbody = json.encode(serializedBody);
+            const type = FullType(BuiltList, [FullType(User)]);
+            final serializedBody = _serializers.serialize(body, specifiedType: type);
+            final jsonbody = json.encode(serializedBody);
             bodyData = jsonbody;
 
             return _dio.request(
@@ -93,7 +93,7 @@ class UserApi {
         /// Creates list of users with given input array
         ///
         /// 
-        Future<Response>createUsersWithListInput(List<User> body,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response>createUsersWithListInput(BuiltList<User> body,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/user/createWithList";
 
@@ -107,9 +107,9 @@ class UserApi {
         List<String> contentTypes = [];
 
 
-            final type = const FullType(BuiltList, const [const FullType(User)]);
-            var serializedBody = _serializers.serialize(BuiltList<User>.from(body), specifiedType: type);
-            var jsonbody = json.encode(serializedBody);
+            const type = FullType(BuiltList, [FullType(User)]);
+            final serializedBody = _serializers.serialize(body, specifiedType: type);
+            final jsonbody = json.encode(serializedBody);
             bodyData = jsonbody;
 
             return _dio.request(
@@ -250,7 +250,7 @@ class UserApi {
             onReceiveProgress: onReceiveProgress,
             ).then((response) {
 
-            var data = response.data as String;
+            final data = response.data as String;
 
             return Response<String>(
                 data: data,
@@ -315,8 +315,8 @@ class UserApi {
         List<String> contentTypes = [];
 
 
-            var serializedBody = _serializers.serialize(body);
-            var jsonbody = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(body);
+            final jsonbody = json.encode(serializedBody);
             bodyData = jsonbody;
 
             return _dio.request(
diff --git a/samples/client/petstore/dart-dio/petstore_client_lib/test/pet_api_test.dart b/samples/client/petstore/dart-dio/petstore_client_lib/test/pet_api_test.dart
index 96c8b9e1c1a..df04da6a5e9 100644
--- a/samples/client/petstore/dart-dio/petstore_client_lib/test/pet_api_test.dart
+++ b/samples/client/petstore/dart-dio/petstore_client_lib/test/pet_api_test.dart
@@ -26,7 +26,7 @@ void main() {
     //
     // Multiple status values can be provided with comma separated strings
     //
-    //Future<List<Pet>> findPetsByStatus(List<String> status) async
+    //Future<BuiltList<Pet>> findPetsByStatus(BuiltList<String> status) async
     test('test findPetsByStatus', () async {
       // TODO
     });
@@ -35,7 +35,7 @@ void main() {
     //
     // Multiple tags can be provided with comma separated strings. Use tag1, tag2, tag3 for testing.
     //
-    //Future<List<Pet>> findPetsByTags(List<String> tags) async
+    //Future<BuiltList<Pet>> findPetsByTags(BuiltList<String> tags) async
     test('test findPetsByTags', () async {
       // TODO
     });
diff --git a/samples/client/petstore/dart-dio/petstore_client_lib/test/store_api_test.dart b/samples/client/petstore/dart-dio/petstore_client_lib/test/store_api_test.dart
index 92d2ff0f5b6..77c6c9d160e 100644
--- a/samples/client/petstore/dart-dio/petstore_client_lib/test/store_api_test.dart
+++ b/samples/client/petstore/dart-dio/petstore_client_lib/test/store_api_test.dart
@@ -21,7 +21,7 @@ void main() {
     //
     // Returns a map of status codes to quantities
     //
-    //Future<Map<String, int>> getInventory() async
+    //Future<BuiltMap<String, int>> getInventory() async
     test('test getInventory', () async {
       // TODO
     });
diff --git a/samples/client/petstore/dart-dio/petstore_client_lib/test/user_api_test.dart b/samples/client/petstore/dart-dio/petstore_client_lib/test/user_api_test.dart
index 618e8a94f89..d3eeaf68ee4 100644
--- a/samples/client/petstore/dart-dio/petstore_client_lib/test/user_api_test.dart
+++ b/samples/client/petstore/dart-dio/petstore_client_lib/test/user_api_test.dart
@@ -19,14 +19,14 @@ void main() {
 
     // Creates list of users with given input array
     //
-    //Future createUsersWithArrayInput(List<User> body) async
+    //Future createUsersWithArrayInput(BuiltList<User> body) async
     test('test createUsersWithArrayInput', () async {
       // TODO
     });
 
     // Creates list of users with given input array
     //
-    //Future createUsersWithListInput(List<User> body) async
+    //Future createUsersWithListInput(BuiltList<User> body) async
     test('test createUsersWithListInput', () async {
       // TODO
     });
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/doc/PetApi.md b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/doc/PetApi.md
index 0119bd4fa41..b8185134f3d 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/doc/PetApi.md
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/doc/PetApi.md
@@ -107,7 +107,7 @@ void (empty response body)
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
 # **findPetsByStatus**
-> List<Pet> findPetsByStatus(status)
+> BuiltList<Pet> findPetsByStatus(status)
 
 Finds Pets by status
 
@@ -120,7 +120,7 @@ import 'package:openapi/api.dart';
 //defaultApiClient.getAuthentication<OAuth>('petstore_auth').accessToken = 'YOUR_ACCESS_TOKEN';
 
 var api_instance = new PetApi();
-var status = []; // List<String> | Status values that need to be considered for filter
+var status = []; // BuiltList<String> | Status values that need to be considered for filter
 
 try { 
     var result = api_instance.findPetsByStatus(status);
@@ -134,11 +134,11 @@ try {
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **status** | [**List&lt;String&gt;**](String.md)| Status values that need to be considered for filter | [default to const []]
+ **status** | [**BuiltList&lt;String&gt;**](String.md)| Status values that need to be considered for filter | [default to const []]
 
 ### Return type
 
-[**List<Pet>**](Pet.md)
+[**BuiltList<Pet>**](Pet.md)
 
 ### Authorization
 
@@ -152,7 +152,7 @@ Name | Type | Description  | Notes
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
 # **findPetsByTags**
-> List<Pet> findPetsByTags(tags)
+> BuiltList<Pet> findPetsByTags(tags)
 
 Finds Pets by tags
 
@@ -165,7 +165,7 @@ import 'package:openapi/api.dart';
 //defaultApiClient.getAuthentication<OAuth>('petstore_auth').accessToken = 'YOUR_ACCESS_TOKEN';
 
 var api_instance = new PetApi();
-var tags = []; // List<String> | Tags to filter by
+var tags = []; // BuiltList<String> | Tags to filter by
 
 try { 
     var result = api_instance.findPetsByTags(tags);
@@ -179,11 +179,11 @@ try {
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **tags** | [**List&lt;String&gt;**](String.md)| Tags to filter by | [default to const []]
+ **tags** | [**BuiltList&lt;String&gt;**](String.md)| Tags to filter by | [default to const []]
 
 ### Return type
 
-[**List<Pet>**](Pet.md)
+[**BuiltList<Pet>**](Pet.md)
 
 ### Authorization
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/doc/StoreApi.md b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/doc/StoreApi.md
index ff948b30a44..4755ee09e69 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/doc/StoreApi.md
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/doc/StoreApi.md
@@ -58,7 +58,7 @@ No authorization required
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
 # **getInventory**
-> Map<String, int> getInventory()
+> BuiltMap<String, int> getInventory()
 
 Returns pet inventories by status
 
@@ -87,7 +87,7 @@ This endpoint does not need any parameter.
 
 ### Return type
 
-**Map<String, int>**
+**BuiltMap<String, int>**
 
 ### Authorization
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/doc/UserApi.md b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/doc/UserApi.md
index 08348d54d24..dfedf9d9e36 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/doc/UserApi.md
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/doc/UserApi.md
@@ -79,7 +79,7 @@ import 'package:openapi/api.dart';
 //defaultApiClient.getAuthentication<ApiKeyAuth>('api_key').apiKeyPrefix = 'Bearer';
 
 var api_instance = new UserApi();
-var user = [new List&lt;User&gt;()]; // List<User> | List of user object
+var user = [new BuiltList&lt;User&gt;()]; // BuiltList<User> | List of user object
 
 try { 
     api_instance.createUsersWithArrayInput(user);
@@ -92,7 +92,7 @@ try {
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **user** | [**List&lt;User&gt;**](User.md)| List of user object | 
+ **user** | [**BuiltList&lt;User&gt;**](User.md)| List of user object | 
 
 ### Return type
 
@@ -123,7 +123,7 @@ import 'package:openapi/api.dart';
 //defaultApiClient.getAuthentication<ApiKeyAuth>('api_key').apiKeyPrefix = 'Bearer';
 
 var api_instance = new UserApi();
-var user = [new List&lt;User&gt;()]; // List<User> | List of user object
+var user = [new BuiltList&lt;User&gt;()]; // BuiltList<User> | List of user object
 
 try { 
     api_instance.createUsersWithListInput(user);
@@ -136,7 +136,7 @@ try {
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **user** | [**List&lt;User&gt;**](User.md)| List of user object | 
+ **user** | [**BuiltList&lt;User&gt;**](User.md)| List of user object | 
 
 ### Return type
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart
index 9f438379d67..28c906b775a 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/pet_api.dart
@@ -2,12 +2,12 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:convert';
 import 'package:dio/dio.dart';
-import 'package:built_collection/built_collection.dart';
 import 'package:built_value/serializer.dart';
 
 import 'package:openapi/model/pet.dart';
 import 'package:openapi/model/api_response.dart';
 import 'dart:typed_data';
+import 'package:built_collection/built_collection.dart';
 import 'package:openapi/api_util.dart';
 
 class PetApi {
@@ -33,8 +33,8 @@ class PetApi {
         List<String> contentTypes = ["application/json","application/xml"];
 
 
-            var serializedBody = _serializers.serialize(pet);
-            var jsonpet = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(pet);
+            final jsonpet = json.encode(serializedBody);
             bodyData = jsonpet;
 
             return _dio.request(
@@ -107,7 +107,7 @@ class PetApi {
         /// Finds Pets by status
         ///
         /// Multiple status values can be provided with comma separated strings
-        Future<Response<List<Pet>>>findPetsByStatus(List<String> status,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response<BuiltList<Pet>>>findPetsByStatus(BuiltList<String> status,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/pet/findByStatus";
 
@@ -140,11 +140,11 @@ class PetApi {
             onReceiveProgress: onReceiveProgress,
             ).then((response) {
 
-            final FullType type = const FullType(BuiltList, const [const FullType(Pet)]);
-            final BuiltList<Pet> dataList = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
-            final data = dataList.toList();
+            const collectionType = BuiltList;
+            const type = FullType(collectionType, [FullType(Pet)]);
+            final BuiltList<Pet> data = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
 
-            return Response<List<Pet>>(
+            return Response<BuiltList<Pet>>(
                 data: data,
                 headers: response.headers,
                 request: response.request,
@@ -158,7 +158,7 @@ class PetApi {
         /// Finds Pets by tags
         ///
         /// Multiple tags can be provided with comma separated strings. Use tag1, tag2, tag3 for testing.
-        Future<Response<List<Pet>>>findPetsByTags(List<String> tags,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response<BuiltList<Pet>>>findPetsByTags(BuiltList<String> tags,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/pet/findByTags";
 
@@ -191,11 +191,11 @@ class PetApi {
             onReceiveProgress: onReceiveProgress,
             ).then((response) {
 
-            final FullType type = const FullType(BuiltList, const [const FullType(Pet)]);
-            final BuiltList<Pet> dataList = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
-            final data = dataList.toList();
+            const collectionType = BuiltList;
+            const type = FullType(collectionType, [FullType(Pet)]);
+            final BuiltList<Pet> data = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
 
-            return Response<List<Pet>>(
+            return Response<BuiltList<Pet>>(
                 data: data,
                 headers: response.headers,
                 request: response.request,
@@ -272,8 +272,8 @@ class PetApi {
         List<String> contentTypes = ["application/json","application/xml"];
 
 
-            var serializedBody = _serializers.serialize(pet);
-            var jsonpet = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(pet);
+            final jsonpet = json.encode(serializedBody);
             bodyData = jsonpet;
 
             return _dio.request(
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart
index a821b9ff078..bbb101e8235 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/store_api.dart
@@ -2,10 +2,10 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:convert';
 import 'package:dio/dio.dart';
-import 'package:built_collection/built_collection.dart';
 import 'package:built_value/serializer.dart';
 
 import 'package:openapi/model/order.dart';
+import 'package:built_collection/built_collection.dart';
 
 class StoreApi {
     final Dio _dio;
@@ -51,7 +51,7 @@ class StoreApi {
         /// Returns pet inventories by status
         ///
         /// Returns a map of status codes to quantities
-        Future<Response<Map<String, int>>>getInventory({ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response<BuiltMap<String, int>>>getInventory({ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/store/inventory";
 
@@ -83,9 +83,11 @@ class StoreApi {
             onReceiveProgress: onReceiveProgress,
             ).then((response) {
 
-            var data = response.data as Map<String, int>;
+            const collectionType = BuiltMap;
+            const type = FullType(collectionType, [FullType(String), FullType(int)]);
+            final BuiltMap<String, int> data = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
 
-            return Response<Map<String, int>>(
+            return Response<BuiltMap<String, int>>(
                 data: data,
                 headers: response.headers,
                 request: response.request,
@@ -162,8 +164,8 @@ class StoreApi {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(order);
-            var jsonorder = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(order);
+            final jsonorder = json.encode(serializedBody);
             bodyData = jsonorder;
 
             return _dio.request(
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart
index 07a794a48f4..e2801bcd924 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/lib/api/user_api.dart
@@ -2,10 +2,10 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:convert';
 import 'package:dio/dio.dart';
-import 'package:built_collection/built_collection.dart';
 import 'package:built_value/serializer.dart';
 
 import 'package:openapi/model/user.dart';
+import 'package:built_collection/built_collection.dart';
 
 class UserApi {
     final Dio _dio;
@@ -30,8 +30,8 @@ class UserApi {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(user);
-            var jsonuser = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(user);
+            final jsonuser = json.encode(serializedBody);
             bodyData = jsonuser;
 
             return _dio.request(
@@ -54,7 +54,7 @@ class UserApi {
         /// Creates list of users with given input array
         ///
         /// 
-        Future<Response>createUsersWithArrayInput(List<User> user,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response>createUsersWithArrayInput(BuiltList<User> user,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/user/createWithArray";
 
@@ -68,9 +68,9 @@ class UserApi {
         List<String> contentTypes = ["application/json"];
 
 
-            final type = const FullType(BuiltList, const [const FullType(User)]);
-            var serializedBody = _serializers.serialize(BuiltList<User>.from(user), specifiedType: type);
-            var jsonuser = json.encode(serializedBody);
+            const type = FullType(BuiltList, [FullType(User)]);
+            final serializedBody = _serializers.serialize(user, specifiedType: type);
+            final jsonuser = json.encode(serializedBody);
             bodyData = jsonuser;
 
             return _dio.request(
@@ -93,7 +93,7 @@ class UserApi {
         /// Creates list of users with given input array
         ///
         /// 
-        Future<Response>createUsersWithListInput(List<User> user,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response>createUsersWithListInput(BuiltList<User> user,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/user/createWithList";
 
@@ -107,9 +107,9 @@ class UserApi {
         List<String> contentTypes = ["application/json"];
 
 
-            final type = const FullType(BuiltList, const [const FullType(User)]);
-            var serializedBody = _serializers.serialize(BuiltList<User>.from(user), specifiedType: type);
-            var jsonuser = json.encode(serializedBody);
+            const type = FullType(BuiltList, [FullType(User)]);
+            final serializedBody = _serializers.serialize(user, specifiedType: type);
+            final jsonuser = json.encode(serializedBody);
             bodyData = jsonuser;
 
             return _dio.request(
@@ -250,7 +250,7 @@ class UserApi {
             onReceiveProgress: onReceiveProgress,
             ).then((response) {
 
-            var data = response.data as String;
+            final data = response.data as String;
 
             return Response<String>(
                 data: data,
@@ -315,8 +315,8 @@ class UserApi {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(user);
-            var jsonuser = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(user);
+            final jsonuser = json.encode(serializedBody);
             bodyData = jsonuser;
 
             return _dio.request(
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/test/pet_api_test.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/test/pet_api_test.dart
index 4cd22a598c1..bdbdcfc07aa 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/test/pet_api_test.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/test/pet_api_test.dart
@@ -26,7 +26,7 @@ void main() {
     //
     // Multiple status values can be provided with comma separated strings
     //
-    //Future<List<Pet>> findPetsByStatus(List<String> status) async
+    //Future<BuiltList<Pet>> findPetsByStatus(BuiltList<String> status) async
     test('test findPetsByStatus', () async {
       // TODO
     });
@@ -35,7 +35,7 @@ void main() {
     //
     // Multiple tags can be provided with comma separated strings. Use tag1, tag2, tag3 for testing.
     //
-    //Future<List<Pet>> findPetsByTags(List<String> tags) async
+    //Future<BuiltList<Pet>> findPetsByTags(BuiltList<String> tags) async
     test('test findPetsByTags', () async {
       // TODO
     });
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/test/store_api_test.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/test/store_api_test.dart
index ae64309d973..27854e9d9cf 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/test/store_api_test.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/test/store_api_test.dart
@@ -21,7 +21,7 @@ void main() {
     //
     // Returns a map of status codes to quantities
     //
-    //Future<Map<String, int>> getInventory() async
+    //Future<BuiltMap<String, int>> getInventory() async
     test('test getInventory', () async {
       // TODO
     });
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/test/user_api_test.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/test/user_api_test.dart
index 9377f97e3c3..b202f3662c4 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/test/user_api_test.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib/test/user_api_test.dart
@@ -19,14 +19,14 @@ void main() {
 
     // Creates list of users with given input array
     //
-    //Future createUsersWithArrayInput(List<User> user) async
+    //Future createUsersWithArrayInput(BuiltList<User> user) async
     test('test createUsersWithArrayInput', () async {
       // TODO
     });
 
     // Creates list of users with given input array
     //
-    //Future createUsersWithListInput(List<User> user) async
+    //Future createUsersWithListInput(BuiltList<User> user) async
     test('test createUsersWithListInput', () async {
       // TODO
     });
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/AdditionalPropertiesClass.md b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/AdditionalPropertiesClass.md
index 4f473ed345b..3371005bbd5 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/AdditionalPropertiesClass.md
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/AdditionalPropertiesClass.md
@@ -9,7 +9,7 @@ import 'package:openapi/api.dart';
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
 **mapProperty** | **BuiltMap&lt;String, String&gt;** |  | [optional] [default to const {}]
-**mapOfMapProperty** | [**BuiltMap&lt;String, BuiltMap&lt;String, String&gt;&gt;**](Map.md) |  | [optional] [default to const {}]
+**mapOfMapProperty** | [**BuiltMap&lt;String, BuiltMap&lt;String, String&gt;&gt;**](BuiltMap.md) |  | [optional] [default to const {}]
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/ArrayOfArrayOfNumberOnly.md b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/ArrayOfArrayOfNumberOnly.md
index 49cf42af14f..e378f671ea1 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/ArrayOfArrayOfNumberOnly.md
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/ArrayOfArrayOfNumberOnly.md
@@ -8,7 +8,7 @@ import 'package:openapi/api.dart';
 ## Properties
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
-**arrayArrayNumber** | [**BuiltList&lt;BuiltList&lt;num&gt;&gt;**](List.md) |  | [optional] [default to const []]
+**arrayArrayNumber** | [**BuiltList&lt;BuiltList&lt;num&gt;&gt;**](BuiltList.md) |  | [optional] [default to const []]
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/ArrayTest.md b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/ArrayTest.md
index db2cd4c9523..3cc123045e8 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/ArrayTest.md
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/ArrayTest.md
@@ -9,8 +9,8 @@ import 'package:openapi/api.dart';
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
 **arrayOfString** | **BuiltList&lt;String&gt;** |  | [optional] [default to const []]
-**arrayArrayOfInteger** | [**BuiltList&lt;BuiltList&lt;int&gt;&gt;**](List.md) |  | [optional] [default to const []]
-**arrayArrayOfModel** | [**BuiltList&lt;BuiltList&lt;ReadOnlyFirst&gt;&gt;**](List.md) |  | [optional] [default to const []]
+**arrayArrayOfInteger** | [**BuiltList&lt;BuiltList&lt;int&gt;&gt;**](BuiltList.md) |  | [optional] [default to const []]
+**arrayArrayOfModel** | [**BuiltList&lt;BuiltList&lt;ReadOnlyFirst&gt;&gt;**](BuiltList.md) |  | [optional] [default to const []]
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/FakeApi.md b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/FakeApi.md
index 20c8e7ecf2f..e7661f82818 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/FakeApi.md
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/FakeApi.md
@@ -492,13 +492,13 @@ To test enum parameters
 import 'package:openapi/api.dart';
 
 var api_instance = new FakeApi();
-var enumHeaderStringArray = []; // List<String> | Header parameter enum test (string array)
+var enumHeaderStringArray = []; // BuiltList<String> | Header parameter enum test (string array)
 var enumHeaderString = enumHeaderString_example; // String | Header parameter enum test (string)
-var enumQueryStringArray = []; // List<String> | Query parameter enum test (string array)
+var enumQueryStringArray = []; // BuiltList<String> | Query parameter enum test (string array)
 var enumQueryString = enumQueryString_example; // String | Query parameter enum test (string)
 var enumQueryInteger = 56; // int | Query parameter enum test (double)
 var enumQueryDouble = 1.2; // double | Query parameter enum test (double)
-var enumFormStringArray = [enumFormStringArray_example]; // List<String> | Form parameter enum test (string array)
+var enumFormStringArray = [enumFormStringArray_example]; // BuiltList<String> | Form parameter enum test (string array)
 var enumFormString = enumFormString_example; // String | Form parameter enum test (string)
 
 try { 
@@ -512,13 +512,13 @@ try {
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **enumHeaderStringArray** | [**List&lt;String&gt;**](String.md)| Header parameter enum test (string array) | [optional] [default to const []]
+ **enumHeaderStringArray** | [**BuiltList&lt;String&gt;**](String.md)| Header parameter enum test (string array) | [optional] [default to const []]
  **enumHeaderString** | **String**| Header parameter enum test (string) | [optional] [default to &#39;-efg&#39;]
- **enumQueryStringArray** | [**List&lt;String&gt;**](String.md)| Query parameter enum test (string array) | [optional] [default to const []]
+ **enumQueryStringArray** | [**BuiltList&lt;String&gt;**](String.md)| Query parameter enum test (string array) | [optional] [default to const []]
  **enumQueryString** | **String**| Query parameter enum test (string) | [optional] [default to &#39;-efg&#39;]
  **enumQueryInteger** | **int**| Query parameter enum test (double) | [optional] [default to null]
  **enumQueryDouble** | **double**| Query parameter enum test (double) | [optional] [default to null]
- **enumFormStringArray** | [**List&lt;String&gt;**](String.md)| Form parameter enum test (string array) | [optional] [default to &#39;$&#39;]
+ **enumFormStringArray** | [**BuiltList&lt;String&gt;**](String.md)| Form parameter enum test (string array) | [optional] [default to &#39;$&#39;]
  **enumFormString** | **String**| Form parameter enum test (string) | [optional] [default to &#39;-efg&#39;]
 
 ### Return type
@@ -601,7 +601,7 @@ test inline additionalProperties
 import 'package:openapi/api.dart';
 
 var api_instance = new FakeApi();
-var requestBody = new Map&lt;String, String&gt;(); // Map<String, String> | request body
+var requestBody = new BuiltMap&lt;String, String&gt;(); // BuiltMap<String, String> | request body
 
 try { 
     api_instance.testInlineAdditionalProperties(requestBody);
@@ -614,7 +614,7 @@ try {
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **requestBody** | [**Map&lt;String, String&gt;**](String.md)| request body | 
+ **requestBody** | [**BuiltMap&lt;String, String&gt;**](String.md)| request body | 
 
 ### Return type
 
@@ -685,11 +685,11 @@ To test the collection format in query parameters
 import 'package:openapi/api.dart';
 
 var api_instance = new FakeApi();
-var pipe = []; // List<String> | 
-var ioutil = []; // List<String> | 
-var http = []; // List<String> | 
-var url = []; // List<String> | 
-var context = []; // List<String> | 
+var pipe = []; // BuiltList<String> | 
+var ioutil = []; // BuiltList<String> | 
+var http = []; // BuiltList<String> | 
+var url = []; // BuiltList<String> | 
+var context = []; // BuiltList<String> | 
 
 try { 
     api_instance.testQueryParameterCollectionFormat(pipe, ioutil, http, url, context);
@@ -702,11 +702,11 @@ try {
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **pipe** | [**List&lt;String&gt;**](String.md)|  | [default to const []]
- **ioutil** | [**List&lt;String&gt;**](String.md)|  | [default to const []]
- **http** | [**List&lt;String&gt;**](String.md)|  | [default to const []]
- **url** | [**List&lt;String&gt;**](String.md)|  | [default to const []]
- **context** | [**List&lt;String&gt;**](String.md)|  | [default to const []]
+ **pipe** | [**BuiltList&lt;String&gt;**](String.md)|  | [default to const []]
+ **ioutil** | [**BuiltList&lt;String&gt;**](String.md)|  | [default to const []]
+ **http** | [**BuiltList&lt;String&gt;**](String.md)|  | [default to const []]
+ **url** | [**BuiltList&lt;String&gt;**](String.md)|  | [default to const []]
+ **context** | [**BuiltList&lt;String&gt;**](String.md)|  | [default to const []]
 
 ### Return type
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/MapTest.md b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/MapTest.md
index c9355eab36d..3a6fa0871ee 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/MapTest.md
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/MapTest.md
@@ -8,7 +8,7 @@ import 'package:openapi/api.dart';
 ## Properties
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
-**mapMapOfString** | [**BuiltMap&lt;String, BuiltMap&lt;String, String&gt;&gt;**](Map.md) |  | [optional] [default to const {}]
+**mapMapOfString** | [**BuiltMap&lt;String, BuiltMap&lt;String, String&gt;&gt;**](BuiltMap.md) |  | [optional] [default to const {}]
 **mapOfEnumString** | **BuiltMap&lt;String, String&gt;** |  | [optional] [default to const {}]
 **directMap** | **BuiltMap&lt;String, bool&gt;** |  | [optional] [default to const {}]
 **indirectMap** | **BuiltMap&lt;String, bool&gt;** |  | [optional] [default to const {}]
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/NullableClass.md b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/NullableClass.md
index 5c3443d6342..bcc17d7f5e5 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/NullableClass.md
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/NullableClass.md
@@ -14,12 +14,12 @@ Name | Type | Description | Notes
 **stringProp** | **String** |  | [optional] [default to null]
 **dateProp** | [**DateTime**](DateTime.md) |  | [optional] [default to null]
 **datetimeProp** | [**DateTime**](DateTime.md) |  | [optional] [default to null]
-**arrayNullableProp** | [**BuiltList&lt;JsonObject&gt;**](Object.md) |  | [optional] [default to const []]
-**arrayAndItemsNullableProp** | [**BuiltList&lt;JsonObject&gt;**](Object.md) |  | [optional] [default to const []]
-**arrayItemsNullable** | [**BuiltList&lt;JsonObject&gt;**](Object.md) |  | [optional] [default to const []]
-**objectNullableProp** | [**BuiltMap&lt;String, JsonObject&gt;**](Object.md) |  | [optional] [default to const {}]
-**objectAndItemsNullableProp** | [**BuiltMap&lt;String, JsonObject&gt;**](Object.md) |  | [optional] [default to const {}]
-**objectItemsNullable** | [**BuiltMap&lt;String, JsonObject&gt;**](Object.md) |  | [optional] [default to const {}]
+**arrayNullableProp** | [**BuiltList&lt;JsonObject&gt;**](JsonObject.md) |  | [optional] [default to const []]
+**arrayAndItemsNullableProp** | [**BuiltList&lt;JsonObject&gt;**](JsonObject.md) |  | [optional] [default to const []]
+**arrayItemsNullable** | [**BuiltList&lt;JsonObject&gt;**](JsonObject.md) |  | [optional] [default to const []]
+**objectNullableProp** | [**BuiltMap&lt;String, JsonObject&gt;**](JsonObject.md) |  | [optional] [default to const {}]
+**objectAndItemsNullableProp** | [**BuiltMap&lt;String, JsonObject&gt;**](JsonObject.md) |  | [optional] [default to const {}]
+**objectItemsNullable** | [**BuiltMap&lt;String, JsonObject&gt;**](JsonObject.md) |  | [optional] [default to const {}]
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/PetApi.md b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/PetApi.md
index 1eb54f8d385..0c22a386f40 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/PetApi.md
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/PetApi.md
@@ -107,7 +107,7 @@ void (empty response body)
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
 # **findPetsByStatus**
-> List<Pet> findPetsByStatus(status)
+> BuiltList<Pet> findPetsByStatus(status)
 
 Finds Pets by status
 
@@ -120,7 +120,7 @@ import 'package:openapi/api.dart';
 //defaultApiClient.getAuthentication<OAuth>('petstore_auth').accessToken = 'YOUR_ACCESS_TOKEN';
 
 var api_instance = new PetApi();
-var status = []; // List<String> | Status values that need to be considered for filter
+var status = []; // BuiltList<String> | Status values that need to be considered for filter
 
 try { 
     var result = api_instance.findPetsByStatus(status);
@@ -134,11 +134,11 @@ try {
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **status** | [**List&lt;String&gt;**](String.md)| Status values that need to be considered for filter | [default to const []]
+ **status** | [**BuiltList&lt;String&gt;**](String.md)| Status values that need to be considered for filter | [default to const []]
 
 ### Return type
 
-[**List<Pet>**](Pet.md)
+[**BuiltList<Pet>**](Pet.md)
 
 ### Authorization
 
@@ -152,7 +152,7 @@ Name | Type | Description  | Notes
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
 # **findPetsByTags**
-> List<Pet> findPetsByTags(tags)
+> BuiltList<Pet> findPetsByTags(tags)
 
 Finds Pets by tags
 
@@ -165,7 +165,7 @@ import 'package:openapi/api.dart';
 //defaultApiClient.getAuthentication<OAuth>('petstore_auth').accessToken = 'YOUR_ACCESS_TOKEN';
 
 var api_instance = new PetApi();
-var tags = []; // List<String> | Tags to filter by
+var tags = []; // BuiltList<String> | Tags to filter by
 
 try { 
     var result = api_instance.findPetsByTags(tags);
@@ -179,11 +179,11 @@ try {
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **tags** | [**List&lt;String&gt;**](String.md)| Tags to filter by | [default to const []]
+ **tags** | [**BuiltList&lt;String&gt;**](String.md)| Tags to filter by | [default to const []]
 
 ### Return type
 
-[**List<Pet>**](Pet.md)
+[**BuiltList<Pet>**](Pet.md)
 
 ### Authorization
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/StoreApi.md b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/StoreApi.md
index 10196b4cfa4..3731ef5fe7f 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/StoreApi.md
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/StoreApi.md
@@ -58,7 +58,7 @@ No authorization required
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
 # **getInventory**
-> Map<String, int> getInventory()
+> BuiltMap<String, int> getInventory()
 
 Returns pet inventories by status
 
@@ -87,7 +87,7 @@ This endpoint does not need any parameter.
 
 ### Return type
 
-**Map<String, int>**
+**BuiltMap<String, int>**
 
 ### Authorization
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/UserApi.md b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/UserApi.md
index f4334518616..16a608ad285 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/UserApi.md
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/doc/UserApi.md
@@ -71,7 +71,7 @@ Creates list of users with given input array
 import 'package:openapi/api.dart';
 
 var api_instance = new UserApi();
-var user = [new List&lt;User&gt;()]; // List<User> | List of user object
+var user = [new BuiltList&lt;User&gt;()]; // BuiltList<User> | List of user object
 
 try { 
     api_instance.createUsersWithArrayInput(user);
@@ -84,7 +84,7 @@ try {
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **user** | [**List&lt;User&gt;**](User.md)| List of user object | 
+ **user** | [**BuiltList&lt;User&gt;**](User.md)| List of user object | 
 
 ### Return type
 
@@ -111,7 +111,7 @@ Creates list of users with given input array
 import 'package:openapi/api.dart';
 
 var api_instance = new UserApi();
-var user = [new List&lt;User&gt;()]; // List<User> | List of user object
+var user = [new BuiltList&lt;User&gt;()]; // BuiltList<User> | List of user object
 
 try { 
     api_instance.createUsersWithListInput(user);
@@ -124,7 +124,7 @@ try {
 
 Name | Type | Description  | Notes
 ------------- | ------------- | ------------- | -------------
- **user** | [**List&lt;User&gt;**](User.md)| List of user object | 
+ **user** | [**BuiltList&lt;User&gt;**](User.md)| List of user object | 
 
 ### Return type
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/another_fake_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/another_fake_api.dart
index f18394e15c8..1d53eac21db 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/another_fake_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/another_fake_api.dart
@@ -2,7 +2,6 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:convert';
 import 'package:dio/dio.dart';
-import 'package:built_collection/built_collection.dart';
 import 'package:built_value/serializer.dart';
 
 import 'package:openapi/model/client.dart';
@@ -30,8 +29,8 @@ class AnotherFakeApi {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(client);
-            var jsonclient = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(client);
+            final jsonclient = json.encode(serializedBody);
             bodyData = jsonclient;
 
             return _dio.request(
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/default_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/default_api.dart
index 8dcef4f418f..61252491155 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/default_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/default_api.dart
@@ -2,7 +2,6 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:convert';
 import 'package:dio/dio.dart';
-import 'package:built_collection/built_collection.dart';
 import 'package:built_value/serializer.dart';
 
 import 'package:openapi/model/inline_response_default.dart';
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_api.dart
index 3ec6259b83f..916e4fbda3f 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_api.dart
@@ -2,7 +2,6 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:convert';
 import 'package:dio/dio.dart';
-import 'package:built_collection/built_collection.dart';
 import 'package:built_value/serializer.dart';
 
 import 'package:openapi/model/client.dart';
@@ -12,6 +11,7 @@ import 'package:openapi/model/user.dart';
 import 'package:openapi/model/health_check_result.dart';
 import 'package:openapi/model/pet.dart';
 import 'dart:typed_data';
+import 'package:built_collection/built_collection.dart';
 import 'package:openapi/api_util.dart';
 
 class FakeApi {
@@ -88,8 +88,8 @@ class FakeApi {
         List<String> contentTypes = ["application/json","application/xml"];
 
 
-            var serializedBody = _serializers.serialize(pet);
-            var jsonpet = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(pet);
+            final jsonpet = json.encode(serializedBody);
             bodyData = jsonpet;
 
             return _dio.request(
@@ -126,8 +126,8 @@ class FakeApi {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(body);
-            var jsonbody = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(body);
+            final jsonbody = json.encode(serializedBody);
             bodyData = jsonbody;
 
             return _dio.request(
@@ -147,7 +147,7 @@ class FakeApi {
             onReceiveProgress: onReceiveProgress,
             ).then((response) {
 
-            var data = response.data as bool;
+            final data = response.data as bool;
 
             return Response<bool>(
                 data: data,
@@ -177,8 +177,8 @@ class FakeApi {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(outerComposite);
-            var jsonouterComposite = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(outerComposite);
+            final jsonouterComposite = json.encode(serializedBody);
             bodyData = jsonouterComposite;
 
             return _dio.request(
@@ -229,8 +229,8 @@ class FakeApi {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(body);
-            var jsonbody = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(body);
+            final jsonbody = json.encode(serializedBody);
             bodyData = jsonbody;
 
             return _dio.request(
@@ -250,7 +250,7 @@ class FakeApi {
             onReceiveProgress: onReceiveProgress,
             ).then((response) {
 
-            var data = response.data as num;
+            final data = response.data as num;
 
             return Response<num>(
                 data: data,
@@ -280,8 +280,8 @@ class FakeApi {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(body);
-            var jsonbody = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(body);
+            final jsonbody = json.encode(serializedBody);
             bodyData = jsonbody;
 
             return _dio.request(
@@ -301,7 +301,7 @@ class FakeApi {
             onReceiveProgress: onReceiveProgress,
             ).then((response) {
 
-            var data = response.data as String;
+            final data = response.data as String;
 
             return Response<String>(
                 data: data,
@@ -331,8 +331,8 @@ class FakeApi {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(fileSchemaTestClass);
-            var jsonfileSchemaTestClass = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(fileSchemaTestClass);
+            final jsonfileSchemaTestClass = json.encode(serializedBody);
             bodyData = jsonfileSchemaTestClass;
 
             return _dio.request(
@@ -370,8 +370,8 @@ class FakeApi {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(user);
-            var jsonuser = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(user);
+            final jsonuser = json.encode(serializedBody);
             bodyData = jsonuser;
 
             return _dio.request(
@@ -408,8 +408,8 @@ class FakeApi {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(client);
-            var jsonclient = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(client);
+            final jsonclient = json.encode(serializedBody);
             bodyData = jsonclient;
 
             return _dio.request(
@@ -497,7 +497,7 @@ class FakeApi {
         /// To test enum parameters
         ///
         /// To test enum parameters
-        Future<Response>testEnumParameters({ List<String> enumHeaderStringArray,String enumHeaderString,List<String> enumQueryStringArray,String enumQueryString,int enumQueryInteger,double enumQueryDouble,List<String> enumFormStringArray,String enumFormString,CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response>testEnumParameters({ BuiltList<String> enumHeaderStringArray,String enumHeaderString,BuiltList<String> enumQueryStringArray,String enumQueryString,int enumQueryInteger,double enumQueryDouble,BuiltList<String> enumFormStringArray,String enumFormString,CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/fake";
 
@@ -583,7 +583,7 @@ class FakeApi {
         /// test inline additionalProperties
         ///
         /// 
-        Future<Response>testInlineAdditionalProperties(Map<String, String> requestBody,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response>testInlineAdditionalProperties(BuiltMap<String, String> requestBody,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/fake/inline-additionalProperties";
 
@@ -597,8 +597,8 @@ class FakeApi {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(requestBody);
-            var jsonrequestBody = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(requestBody);
+            final jsonrequestBody = json.encode(serializedBody);
             bodyData = jsonrequestBody;
 
             return _dio.request(
@@ -660,7 +660,7 @@ class FakeApi {
         /// 
         ///
         /// To test the collection format in query parameters
-        Future<Response>testQueryParameterCollectionFormat(List<String> pipe,List<String> ioutil,List<String> http,List<String> url,List<String> context,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response>testQueryParameterCollectionFormat(BuiltList<String> pipe,BuiltList<String> ioutil,BuiltList<String> http,BuiltList<String> url,BuiltList<String> context,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/fake/test-query-paramters";
 
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_classname_tags123_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_classname_tags123_api.dart
index 1e87b70e59d..6bb3607e11d 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_classname_tags123_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/fake_classname_tags123_api.dart
@@ -2,7 +2,6 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:convert';
 import 'package:dio/dio.dart';
-import 'package:built_collection/built_collection.dart';
 import 'package:built_value/serializer.dart';
 
 import 'package:openapi/model/client.dart';
@@ -30,8 +29,8 @@ class FakeClassnameTags123Api {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(client);
-            var jsonclient = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(client);
+            final jsonclient = json.encode(serializedBody);
             bodyData = jsonclient;
 
             return _dio.request(
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/pet_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/pet_api.dart
index 3f11f5fffe1..45a34674ae6 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/pet_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/pet_api.dart
@@ -2,12 +2,12 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:convert';
 import 'package:dio/dio.dart';
-import 'package:built_collection/built_collection.dart';
 import 'package:built_value/serializer.dart';
 
 import 'package:openapi/model/pet.dart';
 import 'package:openapi/model/api_response.dart';
 import 'dart:typed_data';
+import 'package:built_collection/built_collection.dart';
 import 'package:openapi/api_util.dart';
 
 class PetApi {
@@ -33,8 +33,8 @@ class PetApi {
         List<String> contentTypes = ["application/json","application/xml"];
 
 
-            var serializedBody = _serializers.serialize(pet);
-            var jsonpet = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(pet);
+            final jsonpet = json.encode(serializedBody);
             bodyData = jsonpet;
 
             return _dio.request(
@@ -93,7 +93,7 @@ class PetApi {
         /// Finds Pets by status
         ///
         /// Multiple status values can be provided with comma separated strings
-        Future<Response<List<Pet>>>findPetsByStatus(List<String> status,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response<BuiltList<Pet>>>findPetsByStatus(BuiltList<String> status,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/pet/findByStatus";
 
@@ -126,11 +126,11 @@ class PetApi {
             onReceiveProgress: onReceiveProgress,
             ).then((response) {
 
-            final FullType type = const FullType(BuiltList, const [const FullType(Pet)]);
-            final BuiltList<Pet> dataList = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
-            final data = dataList.toList();
+            const collectionType = BuiltList;
+            const type = FullType(collectionType, [FullType(Pet)]);
+            final BuiltList<Pet> data = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
 
-            return Response<List<Pet>>(
+            return Response<BuiltList<Pet>>(
                 data: data,
                 headers: response.headers,
                 request: response.request,
@@ -144,7 +144,7 @@ class PetApi {
         /// Finds Pets by tags
         ///
         /// Multiple tags can be provided with comma separated strings. Use tag1, tag2, tag3 for testing.
-        Future<Response<List<Pet>>>findPetsByTags(List<String> tags,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response<BuiltList<Pet>>>findPetsByTags(BuiltList<String> tags,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/pet/findByTags";
 
@@ -177,11 +177,11 @@ class PetApi {
             onReceiveProgress: onReceiveProgress,
             ).then((response) {
 
-            final FullType type = const FullType(BuiltList, const [const FullType(Pet)]);
-            final BuiltList<Pet> dataList = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
-            final data = dataList.toList();
+            const collectionType = BuiltList;
+            const type = FullType(collectionType, [FullType(Pet)]);
+            final BuiltList<Pet> data = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
 
-            return Response<List<Pet>>(
+            return Response<BuiltList<Pet>>(
                 data: data,
                 headers: response.headers,
                 request: response.request,
@@ -258,8 +258,8 @@ class PetApi {
         List<String> contentTypes = ["application/json","application/xml"];
 
 
-            var serializedBody = _serializers.serialize(pet);
-            var jsonpet = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(pet);
+            final jsonpet = json.encode(serializedBody);
             bodyData = jsonpet;
 
             return _dio.request(
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/store_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/store_api.dart
index 140b27ae3b4..5f43c7dc8ca 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/store_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/store_api.dart
@@ -2,10 +2,10 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:convert';
 import 'package:dio/dio.dart';
-import 'package:built_collection/built_collection.dart';
 import 'package:built_value/serializer.dart';
 
 import 'package:openapi/model/order.dart';
+import 'package:built_collection/built_collection.dart';
 
 class StoreApi {
     final Dio _dio;
@@ -51,7 +51,7 @@ class StoreApi {
         /// Returns pet inventories by status
         ///
         /// Returns a map of status codes to quantities
-        Future<Response<Map<String, int>>>getInventory({ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response<BuiltMap<String, int>>>getInventory({ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/store/inventory";
 
@@ -83,9 +83,11 @@ class StoreApi {
             onReceiveProgress: onReceiveProgress,
             ).then((response) {
 
-            var data = response.data as Map<String, int>;
+            const collectionType = BuiltMap;
+            const type = FullType(collectionType, [FullType(String), FullType(int)]);
+            final BuiltMap<String, int> data = _serializers.deserialize(response.data is String ? jsonDecode(response.data) : response.data, specifiedType: type);
 
-            return Response<Map<String, int>>(
+            return Response<BuiltMap<String, int>>(
                 data: data,
                 headers: response.headers,
                 request: response.request,
@@ -162,8 +164,8 @@ class StoreApi {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(order);
-            var jsonorder = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(order);
+            final jsonorder = json.encode(serializedBody);
             bodyData = jsonorder;
 
             return _dio.request(
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/user_api.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/user_api.dart
index 4ccd843dfd9..f99d40f56ac 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/user_api.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/lib/api/user_api.dart
@@ -2,10 +2,10 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:convert';
 import 'package:dio/dio.dart';
-import 'package:built_collection/built_collection.dart';
 import 'package:built_value/serializer.dart';
 
 import 'package:openapi/model/user.dart';
+import 'package:built_collection/built_collection.dart';
 
 class UserApi {
     final Dio _dio;
@@ -30,8 +30,8 @@ class UserApi {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(user);
-            var jsonuser = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(user);
+            final jsonuser = json.encode(serializedBody);
             bodyData = jsonuser;
 
             return _dio.request(
@@ -54,7 +54,7 @@ class UserApi {
         /// Creates list of users with given input array
         ///
         /// 
-        Future<Response>createUsersWithArrayInput(List<User> user,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response>createUsersWithArrayInput(BuiltList<User> user,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/user/createWithArray";
 
@@ -68,9 +68,9 @@ class UserApi {
         List<String> contentTypes = ["application/json"];
 
 
-            final type = const FullType(BuiltList, const [const FullType(User)]);
-            var serializedBody = _serializers.serialize(BuiltList<User>.from(user), specifiedType: type);
-            var jsonuser = json.encode(serializedBody);
+            const type = FullType(BuiltList, [FullType(User)]);
+            final serializedBody = _serializers.serialize(user, specifiedType: type);
+            final jsonuser = json.encode(serializedBody);
             bodyData = jsonuser;
 
             return _dio.request(
@@ -93,7 +93,7 @@ class UserApi {
         /// Creates list of users with given input array
         ///
         /// 
-        Future<Response>createUsersWithListInput(List<User> user,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
+        Future<Response>createUsersWithListInput(BuiltList<User> user,{ CancelToken cancelToken, Map<String, String> headers, ProgressCallback onSendProgress, ProgressCallback onReceiveProgress,}) async {
 
         String _path = "/user/createWithList";
 
@@ -107,9 +107,9 @@ class UserApi {
         List<String> contentTypes = ["application/json"];
 
 
-            final type = const FullType(BuiltList, const [const FullType(User)]);
-            var serializedBody = _serializers.serialize(BuiltList<User>.from(user), specifiedType: type);
-            var jsonuser = json.encode(serializedBody);
+            const type = FullType(BuiltList, [FullType(User)]);
+            final serializedBody = _serializers.serialize(user, specifiedType: type);
+            final jsonuser = json.encode(serializedBody);
             bodyData = jsonuser;
 
             return _dio.request(
@@ -250,7 +250,7 @@ class UserApi {
             onReceiveProgress: onReceiveProgress,
             ).then((response) {
 
-            var data = response.data as String;
+            final data = response.data as String;
 
             return Response<String>(
                 data: data,
@@ -315,8 +315,8 @@ class UserApi {
         List<String> contentTypes = ["application/json"];
 
 
-            var serializedBody = _serializers.serialize(user);
-            var jsonuser = json.encode(serializedBody);
+            final serializedBody = _serializers.serialize(user);
+            final jsonuser = json.encode(serializedBody);
             bodyData = jsonuser;
 
             return _dio.request(
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/fake_api_test.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/fake_api_test.dart
index 3fc5ab60ada..0ffe770cdd4 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/fake_api_test.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/fake_api_test.dart
@@ -84,7 +84,7 @@ void main() {
     //
     // To test enum parameters
     //
-    //Future testEnumParameters({ List<String> enumHeaderStringArray, String enumHeaderString, List<String> enumQueryStringArray, String enumQueryString, int enumQueryInteger, double enumQueryDouble, List<String> enumFormStringArray, String enumFormString }) async
+    //Future testEnumParameters({ BuiltList<String> enumHeaderStringArray, String enumHeaderString, BuiltList<String> enumQueryStringArray, String enumQueryString, int enumQueryInteger, double enumQueryDouble, BuiltList<String> enumFormStringArray, String enumFormString }) async
     test('test testEnumParameters', () async {
       // TODO
     });
@@ -100,7 +100,7 @@ void main() {
 
     // test inline additionalProperties
     //
-    //Future testInlineAdditionalProperties(Map<String, String> requestBody) async
+    //Future testInlineAdditionalProperties(BuiltMap<String, String> requestBody) async
     test('test testInlineAdditionalProperties', () async {
       // TODO
     });
@@ -114,7 +114,7 @@ void main() {
 
     // To test the collection format in query parameters
     //
-    //Future testQueryParameterCollectionFormat(List<String> pipe, List<String> ioutil, List<String> http, List<String> url, List<String> context) async
+    //Future testQueryParameterCollectionFormat(BuiltList<String> pipe, BuiltList<String> ioutil, BuiltList<String> http, BuiltList<String> url, BuiltList<String> context) async
     test('test testQueryParameterCollectionFormat', () async {
       // TODO
     });
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/pet_api_test.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/pet_api_test.dart
index a576981450b..7724f48b5df 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/pet_api_test.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/pet_api_test.dart
@@ -26,7 +26,7 @@ void main() {
     //
     // Multiple status values can be provided with comma separated strings
     //
-    //Future<List<Pet>> findPetsByStatus(List<String> status) async
+    //Future<BuiltList<Pet>> findPetsByStatus(BuiltList<String> status) async
     test('test findPetsByStatus', () async {
       // TODO
     });
@@ -35,7 +35,7 @@ void main() {
     //
     // Multiple tags can be provided with comma separated strings. Use tag1, tag2, tag3 for testing.
     //
-    //Future<List<Pet>> findPetsByTags(List<String> tags) async
+    //Future<BuiltList<Pet>> findPetsByTags(BuiltList<String> tags) async
     test('test findPetsByTags', () async {
       // TODO
     });
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/store_api_test.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/store_api_test.dart
index ae64309d973..27854e9d9cf 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/store_api_test.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/store_api_test.dart
@@ -21,7 +21,7 @@ void main() {
     //
     // Returns a map of status codes to quantities
     //
-    //Future<Map<String, int>> getInventory() async
+    //Future<BuiltMap<String, int>> getInventory() async
     test('test getInventory', () async {
       // TODO
     });
diff --git a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/user_api_test.dart b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/user_api_test.dart
index 9377f97e3c3..b202f3662c4 100644
--- a/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/user_api_test.dart
+++ b/samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake/test/user_api_test.dart
@@ -19,14 +19,14 @@ void main() {
 
     // Creates list of users with given input array
     //
-    //Future createUsersWithArrayInput(List<User> user) async
+    //Future createUsersWithArrayInput(BuiltList<User> user) async
     test('test createUsersWithArrayInput', () async {
       // TODO
     });
 
     // Creates list of users with given input array
     //
-    //Future createUsersWithListInput(List<User> user) async
+    //Future createUsersWithListInput(BuiltList<User> user) async
     test('test createUsersWithListInput', () async {
       // TODO
     });