Thank you for investing your time and effort in contributing to our project, we appreciate it a lot! 🤗

General guidelines

For new integrations, please consider adding it in community repo first.
If you want to contribute a bug fix or a new feature that isn't listed in the issues yet, please open a new issue for it. We will prioritize is shortly.
Follow Google's Best Practices for Java Libraries
Keep the code compatible with Java 17.
Avoid adding new dependencies as much as possible (new dependencies with test scope are OK). If absolutely necessary, try to use the same libraries which are already used in the project. Make sure you run mvn dependency:analyze to identify unnecessary dependencies.
Write unit and/or integration tests for your code. This is critical: no tests, no review!
The tests should cover both positive and negative cases.
Make sure you run all unit tests on all modules with mvn clean test
Avoid making breaking changes. Always keep backward compatibility in mind. For example, instead of removing fields/methods/etc, mark them @Deprecated and make sure they still work as before.
Follow existing naming conventions.
Avoid using Lombok in the new code, and remove it from the old code if you get a chance.
Add Javadoc where necessary. There's no need to duplicate Javadoc from the implemented interfaces.
Follow existing code style present in the project. Run make lint and make format before commit.
Large features should be discussed with maintainers before implementation. Please ping @langchain4j in the comments on the issue.

Priorities

All issues are prioritized by maintainers. There are 4 priorities: P1, P2, P3 and P4.

Please start with the higher priorities. PRs will be reviewed in order of priority, with bugs being a higher priority than new features.

Please note that we do not have the capacity to review PRs immediately. We ask for your patience. We are doing our best to review your PR as quickly as possible.

Opening an issue

Please fill in all sections of the issue template.

Opening a draft PR

Please open the PR as a draft initially. Once it is reviewed and approved, we will then ask you to finalize it (see section below).
Fill in all the sections of the PR template.
Please make it easier to review your PR:
- Keep changes as small as possible.
- Do not combine refactoring with changes in a single PR.
- Avoid reformatting existing code.

Finalizing the draft PR

Add documentation (if required).
Add an example to the examples repository (if required).
Run ./mvnw spotless:check and ./mvnw spotless:apply to ensure compliance with the source code formatting of the project.
Mark a PR as ready for review

Guidelines on adding a new model integration

Please open PRs with new model integrations in the langchain4j-community repository
Integration with OpenAI is a good example.
Use the official SDK if available.
If the official SDK is not available, use langchain4j-http-client and Jackson to implement the client.
Create integration test classes that extend from AbstractChatModelIT, AbstractStreamingChatModelIT, AbstractChatModelListenerIT, AbstractStreamingChatModelListenerIT and AbstractStreamingAiServiceIT. There are many examples in existing modules.
If model provider supports tools, create an integration test class that extends from AbstractAiServiceWithToolsIT. There are many examples in existing modules.
If model provider supports structured outputs, create an integration test class that extends from AbstractAiServiceWithJsonSchemaIT. There are many examples in existing modules.
Document the new integration here, here and here.
Add an example to the examples repository, similar to this.
Add a new module to the appropriate section of the BOM.
It would be great if you could add a Spring Boot starter.

Guidelines on adding a new embedding store integration

Please open PRs with new embedding store integrations in the langchain4j-community repository
Integration with Chroma is a good example.
Use the official SDK if available.
If the official SDK is not available, use langchain4j-http-client and Jackson to implement the client.
Add a {IntegrationName}EmbeddingStoreIT. It should extend from EmbeddingStoreWithFilteringIT (when store supports metadata filtering) or EmbeddingStoreIT and pass all tests.
Add a {IntegrationName}EmbeddingStoreRemovalIT. It should extend from EmbeddingStoreWithRemovalIT and pass all tests.
Document the new integration here, here and here.
Add an example to the examples repository, similar to this.
Add a new module to the appropriate section of the BOM.
It would be great if you could add a Spring Boot starter. (after

Guidelines on changing an existing embedding store integration

Ensure that your changes are backwards compatible. Embeddings and TextSegments persisted with the latest released version of LangChain4j should still work.

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