Allow extension of Neo4jContainer class

[portovep]

My team is trying to use Neo4jContainer in a Kotlin codebase but we have an issue with type inference.
Seems like Kotlin cannot infer the type when creating an instance of Neo4jContainer. The following code causes a type inference error:

val myNeo4jContainer = Neo4jContainer("imageName")

To fix it, a custom class that extends from Neo4jContainer needs
to be declared, for example:

class KNeo4jContainer(imageName: String) : Neo4jContainer<KNeo4jContainer>(imageName)

val myNeo4jContainer = KNeo4jContainer("imageName")

This change enables extending the Neo4jContainer class.

[rnorth]

Hi @portovep

Thanks for the PR. I'd say we're absolutely fine to remove the final keyword - that's no problem.

FYI we are considering other changes to our APIs to eliminate the self-typing and make things more Kotlin friendly in general. There's a very difficult balance to strike between usability, extends-ability and the fluent setter model. Unfortunately what looked like the least worst option a couple of years ago isn't the best thing for use with Kotlin now.

Thanks for the contribution!
Richard

[rnorth]

Released in https://github.com/testcontainers/testcontainers-java/releases/tag/1.10.7!

[michael-simons]

Interesting, so type inference doesn't work with final java classes? Good to know! Thanks!