KT-4727 J2K: Convert Java code copied from browser or other sources

#KT-4727 Fixed

idea/testData/copyPaste/plainTextConversion/PostProcessing.expected.kt

@@ -0,0 +1,14 @@
+package to
+
+import java.io.File
+import java.util.ArrayList
+
+internal class JavaClass {
+    fun foo(file: File?, target: MutableList<String>?) {
+        val list = ArrayList<String>()
+        if (file != null) {
+            list.add(file.name)
+        }
+        target?.addAll(list)
+    }
+}