[SPARK-29411] Remove use of Unit companion object in favor of ()

• Type: Sub-task
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.0.0
• Fix Version/s: 3.0.0
• Component/s: ML, Spark Core
• Assignee: Sean R. Owen
• Reporter: Sean R. Owen
• Created: 09/Oct/19 14:25
• Updated: 09/Oct/19 18:26
• Resolved: 09/Oct/19 17:24

Description

Scala 2.13 disallows use of the Unit companion object:

scala> val bar = (i:Int) => Unit
                            ^
       error: `Unit` companion object is not allowed in source; instead, use `()` for the unit value

In these cases, where it's used to mean the Unit object, just use ().

Issue Links

• links to: GitHub Pull Request #26070