Converter:

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

j2k/tests/testData/ast/methodCallExpression/genericMethod.ide.kt

@@ -1,10 +1,10 @@
 package demo
 open class Map() {
-open fun put<K, V>(k : K, v : V) : Unit {
+open fun put<K, V>(k : K, v : V) {
 }
 }
 open class U() {
-open fun test() : Unit {
+open fun test() {
 val m = Map()
 m.put<String, Int>("10", 10)
 }

j2k/tests/testData/ast/methodCallExpression/genericMethod.kt

@@ -1,10 +1,10 @@
 package demo
 open class Map() {
-open fun put<K, V>(k : K?, v : V?) : Unit {
+open fun put<K, V>(k : K?, v : V?) {
 }
 }
 open class U() {
-open fun test() : Unit {
+open fun test() {
 var m : Map? = Map()
 m?.put<String?, Int>("10", 10)
 }