[java] implement #18032 add builder pattern to java client and spring generator

[wing328]

based on #18648

Fix #18032. Add a new configOptions: generateBuilders to java client and spring generators

The name of the option is the same as in JavaJAXSRSSpecServerCodeGen.

Spring + lombok: generateBuilders + generateConstructorWithAllArgs configOptions can be used instead of lombok.

The builder is not created when lombok.Data is configured (issue with fluent setters not generated)

Improve generation of no args constructor.
Also minor fix for the generateConstructorWithAllArgs and Lombok.AllArgsConstructor (there was some typos)

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cc @bbdouglas (2017/07) @sreeshas (2017/08) @jfiala (2017/08) @lukoyanov (2017/09) @cbornet (2017/09) @jeff9finger (2018/01) @karismann (2019/03) @Zomzog (2019/04) @lwlee2608 (2019/10) @martin-mfg (2023/08)
Java Spring | @cachescrubber (2022/02) @welshm (2022/02) @MelleD (2022/02) @atextor (2022/02) @manedev79 (2022/02) @javisst (2022/02) @borsch (2022/02) @banlevente (2022/02) @Zomzog (2022/09) @martin-mfg (2023/08)

[wing328]

thanks for the PR. let's give it a try

[jpfinne]

@wing328 The builder option is missing from the 7.6.0 release notes.
Is that on purpose because it is not production ready?

[wing328]

just updated it to highlight this change as well.

(the release notes are only the highlight, not the full list of changes)

[kevin1chun]

@wing328 is this available in java-webclient as well?

[jpfinne]

@kevin1chun I'm the main contributor of this feature.
I've not done tests with java-webclient. Nevertheless, the WebClient generator shares the same JavaCodeGen and pojo.mustache as the Resttemplate generator. So I would say yes, this is available for you.

Feedbacks are welcome

[kevin1chun]

Thanks @jpfinne
I've successfully integrated the builders into my java-webclient codegen.
It is much cleaner now :)

[laurentperez]

Hi

How would you pass the option in the command below ? Both do not produce builder code.

java -jar openapi-generator-cli.jar generate -g java -i xxxxx.json --additional-properties=generateBuilders=true -o .

java -jar openapi-generator-cli.jar generate -g java -i xxxx.json -p generateBuilders=true -o 

[jpfinne]

@laurentperez

You need to add a space after additional-properties:

java -jar openapi-generator-cli.jar generate -g java -i xxx.jason -o gen --additional-properties  generateBuilders=true --library resttemplate

Even if the code is in AbstractJavaCodeGen, not all libraries are tested with the bulder.
resttemplate, native, spring have a pojo.mustache containing these lines:

{{#generateBuilders}}
  {{>javaBuilder}}
{{/generateBuilders}}

See end of https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/Java/libraries/native/pojo.mustache

If you want to use the builder in the default java library, you need to take a copy of https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/pojo.mustache
and to add the 3 lines with the builder partial.

This can be done with the template customization. See https://openapi-generator.tech/docs/templating/