Apache Spark building on Scala 2.12 (opens in new tab)

This was a long and major effort, awesome to see it completed. I believe the underlying issue holding Flink back from 2.12 support was also the ClosureCleaner taken from Spark[0].

[0] https://github.com/apache/flink/blob/dacc16b4fa6db6abfdbf73b...