Merge branch 'master' into nullpointer-settings-fixes

* master: (45 commits)
  update python samples
  Two tiny fixes for Java Vertx client (#3683)
  Exclude "test" from packages so that it is not installed as top-level package when "pip installing" the generated sdk (#3731)
  [java-client] add unit test for JDK 11 HttpClient (#3735)
  [R] feat(r): handling error response for 3xx cases (#3571)
  [Dart] Avoid redundant null checking in fromJson (#3632)
  [core] Set isMultipart=true for multipart operations, fix possible NPE (#3750)
  reenable kotlin client tests in shippable ci (#3751)
  Fix null assignation to header/query param map (#3749)
  Mockito 3.0.0 (#3732)
  Update to swagger-parser to 2.0.14-OpenAPITools.org-1 (#3737)
  Add a link to a Qiita blog post (#3747)
  update csharp samples
  Simple spelling error in dotnet core comments (#3746)
  better support for multipart (#3736)
  [typescript-fetch] fix #1998: prefix req ifaces. (#3740)
  cpp-qt5-client: add valgrind memory test (#3663)
  [typescript-angular] Encode objects for multipart/form-data with json - fixes #2733 (#3738)
  [BUG] Https protocol schema is not handled correctly in java 11 native code #3729 (#3730)
  comment out kotlin client tests
  ...

.travis.yml

@@ -94,6 +94,8 @@ before_install:
   # - Rely on `kerl` for [pre-compiled versions available](https://docs.travis-ci.com/user/languages/erlang#Choosing-OTP-releases-to-test-against). Rely on installation path chosen by [`travis-erlang-builder`](https://github.com/travis-ci/travis-erlang-builder/blob/e6d016b1a91ca7ecac5a5a46395bde917ea13d36/bin/compile#L18).
   # - . ~/otp/18.2.1/activate && erl -version
   #- curl -f -L -o ./rebar3 https://s3.amazonaws.com/rebar3/rebar3 && chmod +x ./rebar3 && ./rebar3 version && export PATH="${TRAVIS_BUILD_DIR}:$PATH"
+  # install valgrind for C++ memory test
+  - sudo apt-get install valgrind
   # install Qt 5.10
   - sudo add-apt-repository --yes ppa:beineri/opt-qt-5.10.1-trusty
   - sudo apt-get update -qq

CI/.drone.yml

@@ -2,6 +2,13 @@ kind: pipeline
 name: default
 
 steps:
+# test Dart 2.x petstore client
+- name: dart2x-test
+  image: google/dart
+  commands:
+  - (cd samples/client/petstore/dart-jaguar/openapi && pub get && pub run build_runner build --delete-conflicting-outputs)
+  - (cd samples/client/petstore/dart-jaguar/flutter_petstore/openapi && pub get && pub run build_runner build --delete-conflicting-outputs)
+  - (cd samples/client/petstore/dart2/openapi && pub get && pub run test)
 # test Java 11 HTTP client
 - name: java11-test
   image: hirokimatsumoto/alpine-openjdk-11	

CI/samples.ci/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces/pom.xml

@@ -0,0 +1,73 @@
+<project>
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>org.openapitools</groupId>
+    <artifactId>TypeScriptFetchBuildPrefixParameterInterfacesPestoreClientTests</artifactId>
+    <packaging>pom</packaging>
+    <version>1.0-SNAPSHOT</version>
+    <name>TS Fetch Petstore Client (with namespacing for parameter interfaces)</name>
+    <build>
+        <plugins>
+            <plugin>
+                <artifactId>maven-dependency-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>copy-dependencies</goal>
+                        </goals>
+                        <configuration>
+                            <outputDirectory>${project.build.directory}</outputDirectory>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>exec-maven-plugin</artifactId>
+                <version>1.2.1</version>
+                <executions>
+                    <execution>
+                        <id>npm-install</id>
+                        <phase>integration-test</phase>
+                        <goals>
+                            <goal>exec</goal>
+                        </goals>
+                        <configuration>
+                            <executable>npm</executable>
+                            <arguments>
+                                <argument>install</argument>
+                            </arguments>
+                        </configuration>
+                    </execution>
+                    <execution>
+                        <id>npm-build</id>
+                        <phase>integration-test</phase>
+                        <goals>
+                            <goal>exec</goal>
+                        </goals>
+                        <configuration>
+                            <executable>npm</executable>
+                            <arguments>
+                                <argument>run</argument>
+                                <argument>build</argument>
+                            </arguments>
+                        </configuration>
+                    </execution>
+                    <execution>
+                        <id>npm-test</id>
+                        <phase>integration-test</phase>
+                        <goals>
+                            <goal>exec</goal>
+                        </goals>
+                        <configuration>
+                            <executable>npm</executable>
+                            <arguments>
+                                <argument>test</argument>
+                            </arguments>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+</project>

README.md

@@ -66,7 +66,7 @@ OpenAPI Generator allows generation of API client libraries (SDK generation), se
 |                                | Languages/Frameworks |
 |-|-|
 **API clients**                  | **ActionScript**, **Ada**, **Apex**, **Bash**, **C**, **C#** (.net 2.0, 3.5 or later), **C++** (cpp-restsdk, Qt5, Tizen), **Clojure**, **Dart (1.x, 2.x)**, **Elixir**, **Elm**, **Eiffel**, **Erlang**, **Go**, **Groovy**, **Haskell** (http-client, Servant), **Java** (Jersey1.x, Jersey2.x, OkHttp, Retrofit1.x, Retrofit2.x, Feign, RestTemplate, RESTEasy, Vertx, Google API Client Library for Java, Rest-assured, Spring 5 Web Client), **Kotlin**, **Lua**, **Node.js/JavaScript** (ES5, ES6, AngularJS with Google Closure Compiler annotations, Flow types), **Objective-C**, **OCaml**, **Perl**, **PHP**, **PowerShell**, **Python**, **R**, **Ruby**, **Rust** (rust, rust-server), **Scala** (akka, http4s, scalaz, swagger-async-httpclient), **Swift** (2.x, 3.x, 4.x), **Typescript** (AngularJS, Angular (2.x - 8.x), Aurelia, Axios, Fetch, Inversify, jQuery, Node, Rxjs)
-**Server stubs**                 | **Ada**, **C#** (ASP.NET Core, NancyFx), **C++** (Pistache, Restbed, Qt5 QHTTPEngine), **Erlang**, **F#** (Giraffe), **Go** (net/http, Gin), **Haskell** (Servant), **Java** (MSF4J, Spring, Undertow, JAX-RS: CDI, CXF, Inflector, RestEasy, Play Framework, [PKMST](https://github.com/ProKarma-Inc/pkmst-getting-started-examples)), **Kotlin** (Spring Boot, Ktor), **PHP** (Laravel, Lumen, Slim, Silex, [Symfony](https://symfony.com/), [Zend Expressive](https://github.com/zendframework/zend-expressive)), **Python** (Flask), **NodeJS**, **Ruby** (Sinatra, Rails5), **Rust** (rust-server), **Scala** ([Finch](https://github.com/finagle/finch), [Lagom](https://github.com/lagom/lagom), [Play](https://www.playframework.com/), Scalatra)
+**Server stubs**                 | **Ada**, **C#** (ASP.NET Core, NancyFx), **C++** (Pistache, Restbed, Qt5 QHTTPEngine), **Erlang**, **F#** (Giraffe), **Go** (net/http, Gin), **Haskell** (Servant), **Java** (MSF4J, Spring, Undertow, JAX-RS: CDI, CXF, Inflector, Jersey, RestEasy, Play Framework, [PKMST](https://github.com/ProKarma-Inc/pkmst-getting-started-examples)), **Kotlin** (Spring Boot, Ktor), **PHP** (Laravel, Lumen, Slim, Silex, [Symfony](https://symfony.com/), [Zend Expressive](https://github.com/zendframework/zend-expressive)), **Python** (Flask), **NodeJS**, **Ruby** (Sinatra, Rails5), **Rust** (rust-server), **Scala** ([Finch](https://github.com/finagle/finch), [Lagom](https://github.com/lagom/lagom), [Play](https://www.playframework.com/), Scalatra)
 **API documentation generators** | **HTML**, **Confluence Wiki**
 **Configuration files**          | [**Apache2**](https://httpd.apache.org/)
 **Others**                       | **GraphQL**, **JMeter**, **MySQL Schema**
@@ -569,6 +569,7 @@ Here are some companies/projects (alphabetical order) using OpenAPI Generator in
 - [Klarna](https://www.klarna.com/)
 - [Metaswitch](https://www.metaswitch.com/)
 - [Myworkout](https://myworkout.com)
+- [Paxos](https://www.paxos.com)
 - [Prometheus/Alertmanager](https://github.com/prometheus/alertmanager)
 - [Raiffeisen Schweiz Genossenschaft](https://www.raiffeisen.ch)
 - [RepreZen API Studio](https://www.reprezen.com/swagger-openapi-code-generation-api-first-microservices-enterprise-development)
@@ -626,6 +627,7 @@ Here are some companies/projects (alphabetical order) using OpenAPI Generator in
 - 2019-07-08 - [OpenAPI Generator にコントリビュートしたら社名が載った話。(CAM) - CAM TECH BLOG](https://tech.cam-inc.co.jp/entry/2019/07/08/140000) by [CAM, Inc.](https://www.cam-inc.co.jp/)
 - 2019-07-14 - [OpenAPI GeneratorでPythonのクライアントライブラリを作成した](https://qiita.com/yuji38kwmt/items/dfb929316a1335a161c0) by [yuji38kwmt](https://qiita.com/yuji38kwmt)
 - 2019-07-19 - [Developer Experience (DX) for Open-Source Projects: How to Engage Developers and Build a Growing Developer Community](https://speakerdeck.com/wing328/developer-experience-dx-for-open-source-projects-english-japanese) by [William Cheng](https://twitter.com/wing328), [中野暁人](https://github.com/ackintosh) at [Open Source Summit Japan 2019](https://events.linuxfoundation.org/events/open-source-summit-japan-2019/)
+- 2019-08-24 - [SwaggerドキュメントからOpenAPI Generatorを使ってモックサーバー作成](https://qiita.com/masayoshi0222/items/4845e4c715d04587c104) by [坂本正義](https://qiita.com/masayoshi0222)
 
 ## [6 - About Us](#table-of-contents)
 
@@ -755,6 +757,7 @@ Here is a list of template creators:
  * Configuration
    * Apache2: @stkrwork
  * Schema
+   * Avro: @sgadouar 
    * GraphQL: @wing328 [:heart:](https://www.patreon.com/wing328)
    * MySQL: @ybelenko
 

bin/openapi3/avro-petstore.sh

@@ -0,0 +1,32 @@
+#!/bin/sh
+
+SCRIPT="$0"
+echo "# START SCRIPT: $SCRIPT"
+
+while [ -h "$SCRIPT" ] ; do
+  ls=`ls -ld "$SCRIPT"`
+  link=`expr "$ls" : '.*-> \(.*\)$'`
+  if expr "$link" : '/.*' > /dev/null; then
+    SCRIPT="$link"
+  else
+    SCRIPT=`dirname "$SCRIPT"`/"$link"
+  fi
+done
+
+if [ ! -d "${APP_DIR}" ]; then
+  APP_DIR=`dirname "$SCRIPT"`/..
+  APP_DIR=`cd "${APP_DIR}"; pwd`
+fi
+
+executable="./modules/openapi-generator-cli/target/openapi-generator-cli.jar"
+
+if [ ! -f "$executable" ]
+then
+  mvn clean package
+fi
+
+# if you've executed sbt assembly previously it will use that instead.
+export JAVA_OPTS="${JAVA_OPTS} -Xmx1024M -DloggerPath=conf/log4j.properties"
+ags="generate -t modules/openapi-generator/src/main/resources/avro-schema -i modules/openapi-generator/src/test/resources/3_0/petstore.yaml -g avro-schema  -o samples/openapi3/schema/petstore/avro-schema $@"
+
+java $JAVA_OPTS -jar $executable $ags

bin/openapi3/typescript-fetch-petstore-all.sh

@@ -4,3 +4,4 @@
 ./bin/openapi3/typescript-fetch-petstore-with-npm-version.sh
 ./bin/openapi3/typescript-fetch-petstore-interfaces.sh
 ./bin/openapi3/typescript-fetch-petstore.sh
+./bin/openapi3/typescript-fetch-petstore-prefix-parameter-interfaces.sh

bin/openapi3/typescript-fetch-petstore-prefix-parameter-interfaces.sh

@@ -0,0 +1,32 @@
+#!/bin/sh
+
+SCRIPT="$0"
+echo "# START SCRIPT: $SCRIPT"
+
+while [ -h "$SCRIPT" ] ; do
+  ls=`ls -ld "$SCRIPT"`
+  link=`expr "$ls" : '.*-> \(.*\)$'`
+  if expr "$link" : '/.*' > /dev/null; then
+    SCRIPT="$link"
+  else
+    SCRIPT=`dirname "$SCRIPT"`/"$link"
+  fi
+done
+
+if [ ! -d "${APP_DIR}" ]; then
+  APP_DIR=`dirname "$SCRIPT"`/..
+  APP_DIR=`cd "${APP_DIR}"; pwd`
+fi
+
+executable="./modules/openapi-generator-cli/target/openapi-generator-cli.jar"
+
+if [ ! -f "$executable" ]
+then
+  mvn clean package
+fi
+
+# if you've executed sbt assembly previously it will use that instead.
+export JAVA_OPTS="${JAVA_OPTS} -Xmx1024M -DloggerPath=conf/log4j.properties"
+ags="generate -i modules/openapi-generator/src/test/resources/3_0/petstore.yaml -g typescript-fetch -o samples/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces --additional-properties prefixParameterInterfaces=true $@"
+
+java $JAVA_OPTS -jar $executable $ags

bin/typescript-fetch-petstore-all.sh

@@ -4,4 +4,5 @@
 ./bin/typescript-fetch-petstore-with-npm-version.sh
 ./bin/typescript-fetch-petstore-interfaces.sh
 ./bin/typescript-fetch-petstore.sh
-./bin/typescript-fetch-petstore-multiple-parameters.sh
+./bin/typescript-fetch-petstore-multiple-parameters.sh
+./bin/typescript-fetch-petstore-prefix-parameter-interfaces.sh

bin/typescript-fetch-petstore-prefix-parameter-interfaces.json

@@ -0,0 +1,7 @@
+{
+  "npmName": "@openapitools/typescript-fetch-petstore",
+  "npmVersion": "1.0.0",
+  "npmRepository" : "https://skimdb.npmjs.com/registry",
+  "snapshot" : false,
+  "prefixParameterInterfaces": true
+}

bin/typescript-fetch-petstore-prefix-parameter-interfaces.sh

@@ -0,0 +1,34 @@
+#!/bin/sh
+
+SCRIPT="$0"
+echo "# START SCRIPT: $SCRIPT"
+
+while [ -h "$SCRIPT" ] ; do
+  ls=`ls -ld "$SCRIPT"`
+  link=`expr "$ls" : '.*-> \(.*\)$'`
+  if expr "$link" : '/.*' > /dev/null; then
+    SCRIPT="$link"
+  else
+    SCRIPT=`dirname "$SCRIPT"`/"$link"
+  fi
+done
+
+if [ ! -d "${APP_DIR}" ]; then
+  APP_DIR=`dirname "$SCRIPT"`/..
+  APP_DIR=`cd "${APP_DIR}"; pwd`
+fi
+
+executable="./modules/openapi-generator-cli/target/openapi-generator-cli.jar"
+
+if [ ! -f "$executable" ]
+then
+  mvn -B clean package
+fi
+
+# if you've executed sbt assembly previously it will use that instead.
+export JAVA_OPTS="${JAVA_OPTS} -Xmx1024M -DloggerPath=conf/log4j.properties"
+ags="generate -i modules/openapi-generator/src/test/resources/2_0/petstore.yaml -g typescript-fetch -c bin/typescript-fetch-petstore-prefix-parameter-interfaces.json -o samples/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces $@"
+
+java $JAVA_OPTS -jar $executable $ags
+
+cp CI/samples.ci/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces/pom.xml samples/client/petstore/typescript-fetch/builds/prefix-parameter-interfaces/pom.xml

bin/utils/ensure-up-to-date

@@ -59,6 +59,9 @@ declare -a scripts=(
 "./bin/apex-petstore.sh"
 "./bin/perl-petstore-all.sh"
 "./bin/dart-jaguar-petstore.sh"
+"./bin/dart-flutter-petstore.sh"
+"./bin/dart-petstore.sh"
+"./bin/dart2-petstore.sh"
 #"./bin/elm-petstore-all.sh"
 "./bin/meta-codegen.sh"
 # OTHERS

bin/windows/typescript-fetch-petstore-all.bat

@@ -5,3 +5,4 @@ call bin\windows\typescript-fetch-petstore-target-es6.bat
 call bin\windows\typescript-fetch-petstore-with-npm-version.bat
 call bin\windows\typescript-fetch-petstore-interfaces.bat
 call bin\windows\typescript-fetch-petstore-multiple-parameters.bat
+call bin\windows\typescript-fetch-petstore-prefix-parameter-interfaces.bat

bin/windows/typescript-fetch-petstore-prefix-parameter-interfaces.bat

@@ -0,0 +1,12 @@
+@ECHO OFF
+
+set executable=.\modules\openapi-generator-cli\target\openapi-generator-cli.jar
+
+If Not Exist %executable% (
+  mvn clean package
+)
+
+REM set JAVA_OPTS=%JAVA_OPTS% -Xmx1024M
+set ags=generate -i modules\openapi-generator\src\test\resources\2_0\petstore.yaml -g typescript-fetch -o samples\client\petstore\typescript-fetch\builds\prefix-parameter-interfaces --additional-properties prefixParameterInterfaces=true
+
+java %JAVA_OPTS% -jar %executable% %ags%

docs/generators.md

@@ -125,6 +125,7 @@ The following generators are available:
 
 
 ## SCHEMA generators
+* [avro-schema (beta)](generators/avro-schema)  
 * [mysql-schema](generators/mysql-schema)  
 
 

docs/generators/avro-schema.md

@@ -0,0 +1,14 @@
+
+---
+id: generator-opts-schema-avro-schema
+title: Config Options for avro-schema
+sidebar_label: avro-schema
+---
+
+| Option | Description | Values | Default |
+| ------ | ----------- | ------ | ------- |
+|sortParamsByRequiredFlag|Sort method arguments to place required parameters before optional parameters.| |true|
+|ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
+|prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
+|packageName|package for generated classes (where supported)| |null|

docs/generators/csharp-netcore.md

@@ -12,7 +12,7 @@ sidebar_label: csharp-netcore
 |sourceFolder|source folder for generated code| |src|
 |packageGuid|The GUID that will be associated with the C# project| |null|
 |interfacePrefix|Prefix interfaces with a community standard or widely accepted prefix.| |I|
-|targetFramework|The target .NET framework version.|<dl><dt>**netstandard1.3**</dt><dd>.NET Standard 1.3 compatible</dd><dt>**netstandard1.4**</dt><dd>.NET Standard 1.4 compatible</dd><dt>**netstandard1.5**</dt><dd>.NET Standard 1.5 compatible</dd><dt>**netstandard1.6**</dt><dd>.NET Standard 1.6 compatible</dd><dt>**netstandard2.0**</dt><dd>.NET Standard 2.0 compatible</dd><dt>**netcoreapp2.0**</dt><dd>.NET Core 2.0 compatible</dd><dl>|v4.6.1|
+|targetFramework|The target .NET framework version.|<dl><dt>**netstandard1.3**</dt><dd>.NET Standard 1.3 compatible</dd><dt>**netstandard1.4**</dt><dd>.NET Standard 1.4 compatible</dd><dt>**netstandard1.5**</dt><dd>.NET Standard 1.5 compatible</dd><dt>**netstandard1.6**</dt><dd>.NET Standard 1.6 compatible</dd><dt>**netstandard2.0**</dt><dd>.NET Standard 2.0 compatible</dd><dt>**netcoreapp2.0**</dt><dd>.NET Core 2.0 compatible</dd><dl>|netstandard2.0|
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name| |PascalCase|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |true|
 |sortParamsByRequiredFlag|Sort method arguments to place required parameters before optional parameters.| |true|
@@ -26,3 +26,4 @@ sidebar_label: csharp-netcore
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |netCoreProjectFile|Use the new format (.NET Core) for .NET project files (.csproj).| |false|
 |validatable|Generates self-validatable models.| |true|
+|caseInsensitiveResponseHeaders|Make API response's headers case-insensitive| |false|

docs/generators/go-experimental.md

@@ -13,4 +13,5 @@ sidebar_label: go-experimental
 |isGoSubmodule|whether the generated Go module is a submodule| |false|
 |withGoCodegenComment|whether to include Go codegen comment to disable Go Lint and collapse by default GitHub in PRs and diffs| |false|
 |withXml|whether to include support for application/xml content type and include XML annotations in the model (works with libraries that provide support for JSON and XML)| |false|
+|enumClassPrefix|Prefix enum with class name| |false|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|

docs/generators/go.md

@@ -13,4 +13,5 @@ sidebar_label: go
 |isGoSubmodule|whether the generated Go module is a submodule| |false|
 |withGoCodegenComment|whether to include Go codegen comment to disable Go Lint and collapse by default GitHub in PRs and diffs| |false|
 |withXml|whether to include support for application/xml content type and include XML annotations in the model (works with libraries that provide support for JSON and XML)| |false|
+|enumClassPrefix|Prefix enum with class name| |false|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|

docs/generators/typescript-fetch.md

@@ -19,3 +19,4 @@ sidebar_label: typescript-fetch
 |npmRepository|Use this property to set an url your private npmRepo in the package.json| |null|
 |withInterfaces|Setting this property to true will generate interfaces next to the default class implementations.| |false|
 |useSingleRequestParameter|Setting this property to true will generate functions with a single argument containing all API endpoint parameters instead of one argument per parameter.| |true|
+|prefixParameterInterfaces|Setting this property to true will generate parameter interface declarations prefixed with API class name to avoid name conflicts.| |false|

docs/migration-from-swagger-codegen.md

@@ -3,7 +3,7 @@ id: swagger-codegen-migration
 title: Migrating from Swagger Codegen
 ---
 
-OpenAPI Generator is a fork of `swagger-codegen` between version `2.3.1` and `2.4.0`.
+OpenAPI Generator is a fork of `swagger-codegen` between version `2.3.1` and `2.4.0`. For the reasons behind the fork, please refer to the [Q&A](https://github.com/OpenAPITools/openapi-generator/blob/master/docs/qna.md).
 This community-driven version called "OpenAPI Generator" provides similar functionalities and can be used as drop-in replacement.
 This guide explains the major differences in order to help you with the migration.
 
@@ -22,6 +22,7 @@ This guide explains the major differences in order to help you with the migratio
   - [New fully qualified name for the classes](#new-fully-qualified-name-for-the-classes)
   - [Body parameter name](#body-parameter-name)
   - [Default basePath](#default-basepath)
+  - [Nullable](#nullable)
 
 ## New docker images
 
@@ -250,3 +251,7 @@ If your API client is using named parameters in the function call (e.g. Perl req
 ## Default basePath
 
 The default `basePath` has been changed from `https://localhost` to `http://localhost` (http without s)
+
+## Nullable
+
+OpenAPI spec v3 has better support for `nullable`. If you're still using OpenAPI/Swagger spec v2, please use `x-nullable: true` instead.