AGENTS.md for contributors

AGENTS.md

@@ -0,0 +1,92 @@
+## Overview
+
+This is the Adyen Java API Library, providing Java developers with an easy way to interact with the Adyen API. The library is a wrapper around the Adyen API, generated from OpenAPI specifications.
+
+## Code Generation
+
+A significant portion of this library, particularly the API services and data models, is automatically generated
+
+- **Engine**: We use [OpenAPI Generator](https://openapi-generator.tech/) with custom [Mustache](https://mustache.github.io/) templates to convert Adyen's OpenAPI specifications into Java code.
+- **Templates**: The custom templates are located in the `/templates` directory. These templates are tailored to fit our custom HTTP client and model structure.
+- **Automation**:
+    - **Centralized**: The primary generation process is managed in a separate repository, [`adyen-sdk-automation`](https://github.com/Adyen/adyen-sdk-automation). Changes to the OpenAPI specs trigger a GitHub workflow in that repository, which generates the code and opens Pull Requests in this library.
+    - **Local**: For development and testing, you must use the [`adyen-sdk-automation`](https://github.com/Adyen/adyen-sdk-automation) repository.
+
+### Local Code Generation
+
+To test new features or changes to the templates, you must run the generation process from a local clone of the `adyen-sdk-automation` repository.
+
+1.  **Clone the automation repository**:
+    ```bash
+    git clone https://github.com/Adyen/adyen-sdk-automation.git
+    ```
+
+2.  **Link this library**: The automation project needs to target your local clone of `adyen-java-api-library`. From inside the `adyen-sdk-automation` directory, run the following commands. This will replace the `java/repo` directory with a symlink to your local project.
+    ```bash
+    rm -rf java/repo
+    ln -s /path/to/your/adyen-java-api-library java/repo
+    ```
+
+3.  **Run the generator**: You can now run the Gradle commands to generate code.
+    - **To generate all services for the Java library**:
+      ```bash
+      ./gradlew :java:services
+      ```
+    - **To generate a single service (e.g., Checkout)**:
+      ```bash
+      ./gradlew :java:checkout
+      ```
+    - **To clean the repository before generating**:
+      ```bash
+      ./gradlew :java:cleanRepo :java:checkout
+      ```
+
+## Core Components
+
+- **`Client.java`**: The central class for configuring the library (API key, environment, etc.) and accessing API services.
+- **`Service.java`**: The base class for all API services, containing the generic HTTP client logic.
+- **`/service`**: This package contains the generated service classes (e.g., `Checkout`, `Management`) that expose methods for specific API endpoints.
+- **`/model`**: This package contains the generated data models used for API requests and responses.
+
+## Development Workflow
+
+This is a standard Maven project.
+
+### Building
+
+To compile the source code, run the tests, and package the project into a JAR file, use:
+
+```bash
+mvn install
+```
+
+### Running Tests
+
+To execute the unit tests:
+
+```bash
+mvn test
+```
+
+### Code Style & Formatting
+
+We use Checkstyle for linting and Spotless for formatting.
+
+- **Check for style violations**:
+  ```bash
+  mvn checkstyle:check
+  ```
+- **Apply formatting**:
+  ```bash
+  mvn spotless:apply
+  ```
+
+The build will fail if there are any Checkstyle violations. Run `spotless:apply` before committing.
+
+## Release Process
+
+The release process is automated via GitHub Actions. When a release is triggered:
+1.  A script determines the next version number (major, minor, or patch).
+2.  The `pom.xml` and other version files are updated.
+3.  A pull request is created with the version bump.
+4.  Once merged, a GitHub release is created, and the new version is published to Maven Central.