Update extra delegated properties operators to enable them in scripts

[orangy]

https://github.com/gradle/gradle-script-kotlin/blob/75f6ad011cd32c6ad2d8a607c5fa7555b6fa4769/src/main/kotlin/org/gradle/script/lang/kotlin/ExtraPropertiesExtensions.kt#L33-L33

Not really useful in the current setting until Kotlin supports local delegated properties (http://kotlin.link/articles/Kotlin-Post-1-0-Roadmap.html)

This is supported in Kotlin 1.1-M03, but you need to change Nothing? to Any? in getValue/setValue signatures.

[sdeleuze]

That would be very useful to be able to do that!

[bamboo]

@orangy Nothing? seems to work just fine, the real problem is that Kotlin chokes on top level delegated extra property definitions.

[orangy]

Nothing? can work when there is no "receiver" instance, since it is null which is assignable to Nothing?. When in a script, receiver is actually a Project and it cannot be assigned to Nothing?, because it is not null.

[bamboo]

Thanks, @orangy, it makes sense. I still find it a bit confusing that Nothing? would work inside a nested function or block but not at the top level.