A DESCRIPTION OF THE PROBLEM :
https://github.com/openjdk/jfx/blob/6bd0e22d7e33a7e24f17a351914c9ab78a0c3398/modules/javafx.base/src/main/java/javafx/collections/ListChangeListener.java#L227

        /**
         * Indicates that the elements between {@link #getFrom()} (inclusive)
         * to {@link #getTo()} exclusive has changed.
         * This is the only optional event type and may not be
         * fired by all ObservableLists.
         * @return true if the current change is an update change.
         * @since JavaFX 2.1
         */
        public boolean wasUpdated() {
            return false;
        }

The Javadocs suggest this method can return true. The code suggests otherwise.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
No steps, this is clearly a bug.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The wasUpdated method should return true under some condition.
ACTUAL -
The wasUpdated method always returns false.

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Not applicable, the implementation is incorrect.
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CUSTOMER SUBMITTED WORKAROUND :
Code must implement conditional logic using logical OR involving the other was* methods.

FREQUENCY : always