In Flink-Mahout (MAHOUT-1570) Flink Java API is used because Scala API caused different strange compilation problems.
But Scala API handles types better than Flink Java API, so it's better to switch to Scala API. It also can solve MAHOUT-1747
Adding support for Apache Flink as a backend for the Mahout DSL
Mahout DSL for Flink: add support for different types of indexes (String, long, etc)