Why we generate separate Kotlin and Java SDKs

Although the Java SDK is written in Kotlin, which is interoperable with Java, its public API differs from the Kotlin SDK’s. Here are some examples:

• OpenAPI nullable schemas are exposed as Optional types for Java and nullable types for Kotlin
• Lazy iterables are exposed as Stream types for Java and Sequence types for Kotlin
• Async operations are exposed using CompletableFuture types for Java and suspend functions for Kotlin

The Java SDK is written in Kotlin because it simplifies code sharing between the Java and Kotlin SDKs, including custom code.

To add custom Java code, create a java/ directory alongside the existing kotlin/ directory. The Kotlin documentation on Java interoperability has guidance and examples you can reference to ensure your Java code works with the Kotlin code we generate.