What is the use case of org.phoebus.pv.PV.onAccessRightsEvent().subscribe()

["Wang, Lin via Tech-talk" <tech-talk at aps.anl.gov>]

Dear all,

I saw the following code snippet to monitor the PV access right in Phoebus and also similar things in pvws,

writable_flow = pv.onAccessRightsEvent()

                      .subscribe(this::writableChanged);

As I understand, the access right of an IOC or an CA gateway is determined by the Access Security Configuration File when started, and the access right can be obtained by the following code,

/** @return <code>true</code> if PV is read-only */

    public boolean isReadonly()

    {

        return pv.isReadonly();

    }

So my question is, in which scenario does the access right of an IOC dynamically change after started and is necessary to be monitored using the onAccessRightEvent() method?

Thanks,

Lin