FilteredList throws IllegalArgumentException when setting null predicate (see below). At the very least it must be document (which would be the easy way out).

On the other hand, it has a constructor without predicate that's explicitly documented to be meant for binding: in such contexts, a null is hard to avoid. And not really necessary: instead of throwing, it might default to ALWAYS (pending documentation) and log the conversion, just as f.i. IntegerProperty does.

        ObservableList<String> list = createObservableList(true);
        // needs a predicate
        FilteredList<String> filtered = list.filtered(p -> false);
        filtered.setPredicate(null);
 
Caused by: java.lang.IllegalArgumentException: Predicate cannot be null.
at javafx.collections.transformation.FilteredList$1.invalidated(FilteredList.java:100)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:111)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:146)
at javafx.collections.transformation.FilteredList.setPredicate(FilteredList.java:127)