Found while randomly looking at the code:

In AccordionBehavior:280, the body of ListChangeListener uses getAddedSubList() while processing removed elements:

```
        private final ListChangeListener<TitledPane> panesListener = c -> {
            while (c.next()) {
                if (c.wasAdded()) {
                    for (final TitledPane tp: c.getAddedSubList()) {
                        tp.focusedProperty().addListener(paneFocusListener);
                    }
                } else if (c.wasRemoved()) {
                    for (final TitledPane tp: c.getAddedSubList()) {
                        tp.focusedProperty().removeListener(paneFocusListener);
                    }
                }
            }
        };
```

This looks like a copy-paste bug which was introduced by RT-32103 / JDK-8123765 on 2013/08/02.

We'd need to check if a similar pattern has been used elsewhere (may be create a script or a regex pattern?)

EDIT: Regex pattern used in Eclipse
(?s)wasRemoved.*getAddedSubList

identified the following places:
AccordionBehavior:280
Rule:269

And the other way around
(?s)wasAdded.*getRemoved
did not turn up any similar issues.