* Convert from and to JSON automatically.
* Document everything with OpenAPI, that can be used by:
    * Interactive documentation systems.
    * Automatic client code generation systems, for many languages.
* Provide 2 interactive documentation web interfaces directly.

---

We just scratched the surface, but you already get the idea of how it all works.

Try changing the line with:

        TaskProvider<Docbook2Xhtml> dslHtml = tasks.register("dslHtml", Docbook2Xhtml.class, task -> {
            task.setGroup("documentation");
            task.setDescription("Generates DSL reference HTML documentation.");
            task.onlyIf(t -> !extension.getQuickFeedback().get());

            task.source(dslStandaloneDocbook);

The MIT License (MIT)

Copyright (c) 2015 Spring, Inc.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is

Please read the [Development - Contributing](https://fastapi.tiangolo.com/contributing/) guidelines in the documentation site....

      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

That documentation will show up in the Swagger UI at `/docs` in your API, and it will let external developers know how to build the *external API*.

This example doesn't implement the callback itself (that could be just a line of code), only the documentation part.

/// tip

The actual callback is just an HTTP request.

   * serializable.
   *
   * @see <a href=
   *     "http://code.google.com/webtoolkit/doc/latest/DevGuideServerCommunication.html#DevGuideSerializableTypes">
   *     Documentation about GWT serialization</a>
   */
  boolean serializable() default false;

  /**
   * When {@code true}, the annotated type is emulated in GWT. The emulated source (also known as

      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

from fastapi import FastAPI

app = FastAPI(docs_url="/documentation", redoc_url=None)


@app.get("/items/")
async def read_items():

import java.util.List;

import org.apache.commons.cli.Option;
import org.junit.jupiter.api.Test;

import static java.util.Objects.nonNull;

/**
 * Pseudo test to generate documentation fragment about supported CLI options. TODO such documentation generation code
 * should not be necessary as unit test but should be run during site generation (Velocity? Doxia macro?)
 */
class CLIManagerDocumentationTest {