Converter:

Omit Unit return type
Refactor handling of Unit type: extract separate object UnitType

j2k/tests/testData/ast/newClassExpression/genericClassInvocation.kt

@@ -1,6 +1,6 @@
 import java.util.LinkedList
 open class User() {
-open fun main() : Unit {
+open fun main() {
 var list : MutableList<String?>? = LinkedList<String?>()
 }
 }