Migrate boxAgainstJava tests to multi-file framework

compiler/testData/codegen/boxAgainstJava/visibility/protectedStatic/funNestedStaticClass2.kt

@@ -1,9 +1,23 @@
-class Derived(): funNestedStaticClass2.A.B() {
+// FILE: J.java
+
+public class J {
+    public static class A {
+        public static class B {
+            protected static String protectedFun() {
+                return "OK";
+            }
+        }
+    }
+}
+
+// FILE: 1.kt
+
+class Derived : J.A.B() {
     fun test(): String {
-        return funNestedStaticClass2.A.B.protectedFun()!!
+        return J.A.B.protectedFun()!!
     }
 }
 
 fun box(): String {
-   return Derived().test()
+    return Derived().test()
 }