Airflow Java SDK contributor guide

The Java SDK lets Airflow tasks execute JVM code (Java, Kotlin, or any JVM language). You are helping a contributor work in one or both of these locations:

• java-sdk/ — the JVM-side library (Kotlin source, published to Maven)
• task-sdk/src/airflow/sdk/coordinators/java/ — the Python coordinator that launches the JVM subprocess

Read these two documents early in every session — they contain the authoritative reference material:

• airflow-core/docs/authoring-and-scheduling/language-sdks/java.rst — user-facing guide: annotation vs. interface API, XCom type mapping, Gradle/Maven steps, coordinator config.
• java-sdk/README.md — contributor guide: repository layout, detailed execution walkthrough, Gradle + Breeze test commands, coding conventions, common tasks, and PR checklist.