Create Java Client

[spacether]

Add a java client to openapi-json-schema-generator

• sample petstore java client is here
• openapi document that the client is created from is here
• Java templates that generate the code
• Java client generator class that ingests the openapi document, processes the data before code generation is invoked

The project to to port it over into Java is here:
https://github.com/orgs/openapi-json-schema-tools/projects/5/views/1

openapi-generator people who want an openapi 3.1.0 java client generator:
My openapi-jscon-schema-generator repo has a python client that works with 3.1.0 documents and it passes mypy static analysis. This project is to port it over into Java. Do any of you want to help build it?
@solczak @PiotrBlue @JakubSawczuk @rmzzz @jackdbrowne @childish-sambino @jurajsallai @namero999 @tschaffter @tzelon-cypator @Beef-Tech @npaturi @dosomder @pmarschik @fdomingues-sky @gbaso @Ivanbmstu @gergelyszaz @Tynamix @swissmalamute @leazhang31 @s-jepsen @anm-cb @WIStudent @ChristianMoesl @alexec @archrk @lchansf @1Guerrilla @abhishekdhabriya @bozhou-flex @snowe2010 @gstanek @scatler @kikones34 @MarcSalvat @dotneutron @Enrice @PhilippMT @xtina @martin-mfg @mnk-se @meden

[spacether]

Two Java clients are now being generated and tested in CI

• (1) the v3.0.3 petstore client
  • Example schema javadoc
• (2) the v3.0.3 unit test client that includes tests from the json schema test suite
  • component schemas javadocs
  • autogen json schema test suite tests
• all v3.0.3 openapi schema keywords/json schema keywords have been implemented except for discriminator (qty 26)
• openapi/json schema validation is working

Tests are passing in CI
Javadocs are generated for all component schemas
parameter/header/requestBody/response features have not yet been implemented

[spacether]

• Map Builder classes are now being generatef for object (map) schemas
• List Builder classes are now being generated for array (list) schemas
• Enums are now generated for schema enums, and may be used in Schema.validate/ListBuilder/MapBuilder inputs
• Java generator is now listed as a possible generator, and will be available in the 4.0.0 release
• The Checker-Framework's NullnessChecker and @Nullable annotations are used in the java client, ensuring that null pointer exceptions will not happen

Further work needs to be done to add openapi features like:

• Servers Java generator, adds schema default + Servers #355
• SecuritySchemes (same ones as python implemented) Java, adds component SecuritySchemes #383
• Security Java adds security to ApiClient #384
• ApiConfiguration Java adds security to ApiClient #384
• RequestBody Java client, adds RequestBody #390
• Response Java client, adds responses #391
• Responses Java client, adds responses class + deserializer #394
• Headers Java client, adds header #396
• Parameters Java client, adds parameter classes #398
• CodegenOperation Java client, adds operations #406

The long term plan is to use sealed classes for use cases like:

• schema validation, output types constrained
• request body inputs
• responses from endpoints, multiple response types may be returned

[spacether]

The version 4.1.0 release now supports Java json schema 2020-12 openapi 3.1.0 schema validation

[spacether]

The java client now exists in master branch and one can make json rest calls with it. Soon I will release it by cutting a new minor version.
Before that happens, I will

• improving the security code and documentation
• add an endpoint code sample

[spacether]

@solczak @PiotrBlue @JakubSawczuk @rmzzz @jackdbrowne @childish-sambino @jurajsallai @namero999 @tschaffter @tzelon-cypator @Beef-Tech @npaturi @dosomder @pmarschik @fdomingues-sky @gbaso @Ivanbmstu @gergelyszaz @Tynamix @swissmalamute @leazhang31 @s-jepsen @anm-cb @WIStudent @ChristianMoesl @alexec @archrk @lchansf @1Guerrilla @abhishekdhabriya @bozhou-flex @snowe2010 @gstanek @scatler @kikones34 @MarcSalvat @dotneutron @Enrice @PhilippMT @xtina @martin-mfg @mnk-se @meden

Please check out the 4.2.1 release of this project which includes a stable Java generator that supports openapi 3.1.0 documents and uses sealed classes for validated schema payloads/request bodies/responses/response bodies