Sending an Ical4J Event via E-Mail using the Publish Method

Question

I am trying to send an E-Mail with an open Event to be included in a private calendar. I brought it to work using the Request-Method, but this was not exactly the behaviour I wanted. I do not want the recipients to answer the "invitation" when including the event in their calendars. I found that out I need to use the Publish-Method instead, but now my code is not working anymore. I needed to delete the Attendee-Property, which makes sense, as the event is public and everyone can include it in their private calendars. But once I do this, I get an E-Mail without Accept/Decline etc. Buttons, but instead I get an E-Mail with all the information but also including the note that I still have to send the E-Mail to the recipients. I am using the net.fortuna.ical4j-library to create the Ical-events, here is my code:

final Calendar calendar = new Calendar();
        final PropertyList properties = calendar.getProperties();
        properties.add(new ProdId("-//my ProdId"));
        properties.add(Version.VERSION_2_0);
        properties.add(CalScale.GREGORIAN);
        properties.add(Method.PUBLISH);

        final Date startDate = new Date(TimeFormats.DATE_8.format(recordAttr.get(ATTR_START_DATE)));
        // let it last exactly one day to get an all-day event
        final Date endDate = new Date(Date.from(LocalDateTime.from(startDate.toInstant().atZone(ZoneId.of("UTC"))).plusDays(1).toInstant(ZoneOffset.UTC)));
        final String name = (String) recordAttr.get(ATTR_NAME);
        final VEvent icalEvent = new VEvent(startDate, endDate, name);

        String recordAttrUid = (String) recordAttr.get(ATTR_UID);
        if (!recordAttrUid.isEmpty())
        {
            this.uid = new Uid(recordAttrUid.split("UID:")[1].replaceAll("([\n\r])", ""));
        }
        else
        {
            final UidGenerator uidGenerator = new UidGenerator(ATTR_UID_GEN);
            this.uid = uidGenerator.generateUid();
        }
        icalEvent.getProperties().add(this.uid);

        icalEvent.getProperties().add(new Priority(5));

        Long sequence = (Long) recordAttr.get(ATTR_SEQUENCE);
        this.sequence = sequence != null ? sequence + 1 : 0;
        icalEvent.getProperties().add(new Sequence(Math.toIntExact(this.sequence)));

        icalEvent.getProperties().add(new Created());
        icalEvent.getProperties().add(new LastModified());
        icalEvent.getProperties().add(new Location());

        final Description description = new Description((String) recordAttr.get(ATTR_DESCRIPTION));
        icalEvent.getProperties().add(description);

        final Organizer organizer = new Organizer("[email protected]");
        organizer.getParameters().add(new SentBy("[email protected]"));
        icalEvent.getProperties().add(organizer);

        final VAlarm vAlarm = new VAlarm(new Dur(0, -1, 0, 0));
        vAlarm.getProperties().add(Action.DISPLAY);
        vAlarm.getProperties().add(new Description((String) recordAttr.get(ATTR_DESCRIPTION)));
        icalEvent.getAlarms().add(vAlarm);

        calendar.getComponents().add(icalEvent);

        this.icsFile = new File(name + ".ics");
        final FileOutputStream fout = new FileOutputStream(this.icsFile);
        final CalendarOutputter outputter = new CalendarOutputter();
        outputter.output(calendar, fout);

This code produces the following ics-String:

BEGIN:VCALENDAR
PRODID:-//my ProdId
VERSION:2.0
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20201210T091704Z
DTSTART;VALUE=DATE:20201210
DTEND;VALUE=DATE:20201211
SUMMARY:e
UID:20201210T091704Z-uidGen@fe80:0:0:0:dd32:894f:88da:fde6%wlan0
PRIORITY:5
SEQUENCE:0
CREATED:20201210T091705Z
LAST-MODIFIED:20201210T091705Z
LOCATION:
DESCRIPTION:
ORGANIZER;[email protected]:[email protected]
BEGIN:VALARM
TRIGGER:-PT1H
ACTION:DISPLAY
DESCRIPTION:
END:VALARM
END:VEVENT
END:VCALENDAR