Nullability Annotations

[ScottPierce]

It would be helpful if RxJava had nullability annotations that might provide warnings to developers in a good IDE. This would be a helpful addition, especially considering RxJava no longer allows streaming of null types.

It would also provide helpful indicators for other JVM languages that have Nullability built in. Kotlin is a good example of this. Currently using RxJava with Kotlin results in most code being interpreted as potentially nullable. Annotating types in the RxJava API would fix this in a way that a side library, like RxKotlin, couldn't.

[akarnokd]

There were several enhancements in this regard in the recent past: #5055, #5051, #5023 for example.

[ScottPierce]

I see. Now that you mention it I see them in certain places, but missing from others. It'd be helpful to have them on the Observer interfaces for instance. The OnSubscribes too, such as ObservableOnSubscribe.

I'm sure there are a few others that are missing them as well, considering how often I see this.

[akarnokd]

PR welcome.

[ScottPierce]

Sounds reasonable.

I had loaded the RxJava gradle project the other day, and came across several gradle errors. I ended up having to comment out a lot of the build.gradle regarding nebula, and animal sniffer to make gradle happy. Any idea why that might have been?

[akarnokd]

Use the gradle in the project: 2.14 . The 3.x don't work properly due to the outdated nebula plugin. In theory, the nebula is just an aggregator of other plugins which appear to be 3.x ready. We could use the help with them too.

[ScottPierce]

Oh right. Because I loaded the project with Android Studio, it forced the gradle wrapper to upgrade to 3.3. I'll just use IntelliJ next time. Thanks!

[akarnokd]

Continuing with #5341.