Prevent use of the same array in CollectionProperty (close #58743)

[emilianbold]

CollectionProperty constructor receives an empty ObjectTableModel.objects
collection but normalizeList will return it as-is instead of creating a
new empty collection.

The two classes share the same array but add different kind of classes.

NOTE: Basically the bug is in AbstractProperty.normalizeList because it should never reuse the same instance. I've done the patch as you see it because it has the lowest impact and does not change the normalizeList API (perhaps reusing is expected in some cases?)

Let me know if I should redo the patch by just changing normalizeList!

Constructor stacktrace:
at org.apache.jmeter.testelement.property.CollectionProperty.(CollectionProperty.java:40)
at org.apache.jmeter.testelement.property.AbstractProperty.makeProperty(AbstractProperty.java:395)
at org.apache.jmeter.testelement.property.AbstractProperty.createProperty(AbstractProperty.java:368)
at org.apache.jmeter.testbeans.gui.TestBeanGUI.setPropertyInElement(TestBeanGUI.java:277)
at org.apache.jmeter.testbeans.gui.TestBeanGUI.modifyTestElement(TestBeanGUI.java:266)
at org.apache.jmeter.gui.tree.JMeterTreeModel.addComponent(JMeterTreeModel.java:148)
at org.apache.jmeter.gui.action.AddToTree.doAction(AddToTree.java:70)
at org.apache.jmeter.gui.action.ActionRouter.performAction(ActionRouter.java:74)
at org.apache.jmeter.gui.action.ActionRouter.lambda$actionPerformed$28(ActionRouter.java:59)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)

[FSchumacher]

Great. Thanks for your analysis and your fix.

I tend to change the behaviour of normalizeList, even if it is a change in the unwritten contract. The current behaviour seems wrong to me. It was probably meant to save space.

[pmouawad]

Thanks for analysis and patch. It was a hard one !.

@FSchumacher , I don't understand your comment , what exactly do you want to change ?
Thanks

[FSchumacher]

As Emilan suggested, we could change normalizeList to always create a new collection, instead of introducing a new method, that has configurable behaviour.

I consider the current behaviour to be a bug.

[pmouawad]

@FSchumacher , I agree. Let's commit the patch without the new method.

[emilianbold]

Ammeding the commit as we speak.

[emilianbold]

Done. The new patch is much cleaner.

[FSchumacher]

Great, I wonder if we should change the return value from null to Collections.emptyList() in case of an Exception, too.

I will add a test case to the bugzilla entry for normalizeList.

[emilianbold]

It's unclear to me why it's so important to use the same kind of collection class. So I tried to keep the patch low-impact.

Instead of null or an empty list it could return a new ArrayList with the objects.

[vherilier]

Hi guys,

could be the same issue available with the next method "normalizeMap"?

[emilianbold]

could be the same issue available with the next method "normalizeMap"?

Actually, yes! Should I update this patch or leave normalizeMap for another fix?

[emilianbold]

Like I've said, I wanted my patch to be low-impact. Ideally normalizeList should be something like this:

    protected Collection<JMeterProperty> normalizeList(Collection<?> coll) {
        return coll.stream()
                .map(this::convertObject)
                .collect(Collectors.toCollection(ArrayList::new));
    }

Then normalizeMap should be like this:

    protected Map<String, JMeterProperty> normalizeMap(Map<?,?> coll) {
        return coll.entrySet()
                .stream()
                .collect(Collectors.toMap(entry -> {
                    Object key = entry.getKey();

                    if (key == null) {
                        return null;
                    } else {
                        if (!(key instanceof String)) {
                            log.error("Expected key type String, found: {}", key.getClass());
                        }
                        return key.toString();
                    }
                }, entry -> convertObject(entry.getValue())));
    }

[pmouawad]

+1 for fixing both methods

[emilianbold]

Done.