While investigating my #2 issue from
https://bugs.openjdk.java.net/browse/JDK-8006183?focusedCommentId=13504584&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13504584
I've noticed a problem with identity. I know the identity of Java objects passed to Nashorn and returned back is weaker than it used to be in Rhino - e.g. sometimes objects are not == only equal. But I found a case where the object is not even equal and I consider it a bug. Would you agree that following testIdentity function should never throw the IllegalStateException?

    public static void main(String[] args) throws Exception {
        ScriptEngineManager sem = new ScriptEngineManager();
        ScriptEngine eng = sem.getEngineByMimeType("text/javascript");
        Invocable inv = (Invocable) eng;

        testIdentity(eng, new Object());
        
    }
    
    private static void testIdentity(ScriptEngine eng, Object obj) throws Exception {
        Invocable inv = (Invocable) eng;

        eng.eval("function id(x) { return x; }");
        
        Object returned = inv.invokeFunction("id", obj);
        
        if (returned == obj || obj.equals(returned)) {
            return;
        }
        throw new IllegalStateException(
          "Not equals! obj: " + obj + " returned: " + returned +
          "\ntypes: " + obj.getClass() + " real: " + returned.getClass()
        );
    }

I would agree with such statement. Having a function that returns is parameter, should return the parameter. At least I hope.