A DESCRIPTION OF THE REQUEST :
PropertyChangeSupport.firePropertyChange(String propertyName, Object oldValue, Object newValue) fires PropertyChange when both values are null. This is not real change and should not firePropertyChange.

JUSTIFICATION :
Avoid infinite loops and StackOverflowException.

ACTUAL -
    /**
     * Report a bound property update to any registered listeners.
     * No event is fired if old and new are equal and non-null.
     *
     * <p>
     * This is merely a convenience wrapper around the more general
     * firePropertyChange method that takes {@code
     * PropertyChangeEvent} value.
     *
     * @param propertyName The programmatic name of the property
     * that was changed.
     * @param oldValue The old value of the property.
     * @param newValue The new value of the property.
     */
    public void firePropertyChange(String propertyName,
Object oldValue, Object newValue) {
if (oldValue != null && newValue != null && oldValue.equals(newValue)) {
return;
}
firePropertyChange(new PropertyChangeEvent(source, propertyName,
oldValue, newValue));
    }

---------- BEGIN SOURCE ----------
if (oldValue != null && newValue != null && oldValue.equals(newValue)) {
return;
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
if (oldValue == null) {
    if (newValue == null) return;
} else {
    if (oldValue.equals(newValue)) return;
}