Flipper: Annotate the code with @Nonnull / @Nullable

[eboudrant]

For better interopt with Kollin. At least the public api code should be annotated.

[passy]

We generally don't use @NotNull internally. Unless something is marked as @Nullable, it should be considered to never be null. I believe there's a Kotlin mode/flag to enable that behaviour?

[Takhion]

@passy indeed there is since Kotlin 1.1.4: @ParametersAreNonnullByDefault

[passy]

@Takhion Nice! We should annotate the package with that.

[justintuchek]

Is anyone actively working on this issue?

Don't want to step on anyones toes but looking at a good first issue to pickup

[recheej]

@passy can you close this? Looks like it's already done by you :)

https://github.com/facebook/flipper/commit/0daa5de428eedd79dd23c695c861d5ae77fda011

[passy]

@recheej Thanks for noting!