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## 2.39.6

**`(feat):`** Add opt-in extensible builder pattern via `enable-extensible-builders` flag. When enabled, builders use the self-type
pattern allowing users to extend generated builders while maintaining type safety. Example:

```java
class CustomBuilder extends BaseClientBuilder<CustomBuilder> {
    @Override
    protected CustomBuilder self() { return this; }

    public CustomBuilder workspaceId(String id) {
        // custom logic
        return this;
    }
}
```

## 2.39.5

**`(fix):`** Fix undiscriminated union deserialization to catch all RuntimeException types instead of just IllegalArgumentException.