Add new AI Java quickstart app to go with new guide

[lauracowen]

Check list:

Your pull request:

• targets the development branch
• uses the 999-SNAPSHOT version of Quarkus
• has tests (mvn clean test)
• works in native (mvn clean package -Pnative)
• has integration/native tests (mvn clean verify -Pnative)
• makes sure the associated guide must not be updated
• links the guide update pull request (if needed)
• updates or creates the README.md file (with build and run instructions)
• for new quickstart, is located in the directory component-quickstart
• for new quickstart, is added to the root pom.xml and README.md

• New guide: New guide to create your first AI Java application quarkus#48136
• It's not intended to work in native so it only has a single unit test file
• I'm not sure what the instruction about component-quickstart means?

[edeandrea]

Wouldn't this belong in the quarkus-langchain4j repo? There is already something similar there (https://github.com/quarkiverse/quarkus-langchain4j/tree/main/samples/email-a-poem).

Someone else can correct me if I'm mis-speaking, but the quickstarts here are for things that are part of Quarkus core and have guides on Quarkus core. Things in Quarkiverse aren't part of Quarkus core.

That being said, I'm not opposed to it at all.

[holly-cummins]

Quarkiverse quickstarts is a tricky topic. See quarkiverse/quarkus-cxf#399 and quarkusio/quarkus#24870 and quarkiverse/quarkiverse-devops#231 for some of the discussion.

The decision across those discussions seems to be that quickstarts should be bundled in with the owning quarkiverse extension. But if the quickstart lives in the extension's repo, the distinction between a quickstart and a sample is not obvious to me. We should probably update https://quarkus.io/guides/extension-faq#whats-the-difference-between-a-quickstart-and-a-codestart with the answer to "what's the difference between a quickstart and a sample,", once we figure it out. :)

On extensions.quarkus.io, we have a section called "samples" which lists both auto-discovered quickstarts and samples, IIRC. See, for example, https://quarkus.io/extensions/io.quarkiverse.langchain4j/quarkus-langchain4j-hugging-face/ or https://quarkus.io/extensions/io.quarkus/quarkus-rest-client/. At the moment it's not got a nice list, just a link to either the quickstart repo or the samples folder in the extension repo.

[lauracowen]

I created this as a quickstart to accompany the guide in the separate PR - I followed the approach in the existing Quarkus "getting started" guides which link out to a quickstart to see the completed app. So I think whatever is decided about the guide probably influences this PR too?