Converter:

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

j2k/tests/testData/ast/callChainExpression/libraryStringFieldCall.kt

@@ -2,7 +2,7 @@ open class Library() {
 public val myString : String? = null
 }
 open class User() {
-open fun main() : Unit {
+open fun main() {
 Library.myString?.isEmpty()
 }
 }