[Test] Properly merge box against java testdata into codegen/box

Previous commit about it was 3199ce03 and it was completely wrong

compiler/testData/codegen/box/sam/adapters/implementAdapter.kt

@@ -0,0 +1,25 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// DONT_TARGET_EXACT_BACKEND: JS JS_IR JS_IR_ES6 WASM NATIVE
+// WITH_RUNTIME
+// MODULE: lib
+// FILE: JavaInterface.java
+
+interface JavaInterface {
+    void foo(Runnable r);
+}
+
+// MODULE: main(lib)
+// FILE: 1.kt
+
+class Impl: JavaInterface {
+    override fun foo(r: Runnable?) {
+        r?.run()
+    }
+}
+
+fun box(): String {
+    val fooMethods = Impl::class.java.getMethods().filter { it.getName() == "foo" }
+    if (fooMethods.size != 1) return fooMethods.toString()
+
+    return "OK"
+}