J2K: coversion of specially mapped built-in methods + replacing "get" with "[]" where possible

j2k/testData/fileOrElement/assignmentExpression/nullability.kt

@@ -4,6 +4,6 @@ internal class Foo {
     fun foo(o: HashSet<Any>) {
         val o2 = o
         var foo = 0
-        foo = o2.size()
+        foo = o2.size
     }
 }