Implementation of nextcloud#12885. Removed the workaround for nextclo…

…ud/3rdparty#191.

Signed-off-by: hdijkema <hans@dykema.nl>

apps/dav/lib/CalDAV/Schedule/IMipPlugin.php

@@ -257,32 +257,6 @@ public function schedule(Message $iTipMessage) {
 		#);
 		#$message->attach($attachment);
 
-		# The plain text text/calendar part is added to the code, but we need
-		# to do something more. Outlook (2010 and 2016 tested) has problems with canceled messages
-		# that contain Time Zone Identifications (e.g. ;TZID=Europe/Amsterdam:).
-		# A 'not-supported-calendar-message.ics' is shown and the cancellation is not recognized.
-		#
-		# See e.g.: https://stackoverflow.com/questions/48550054/icalendar-appointment-is-a-not-supported-calendar-message-ics
-		#
-		# To work around this problem, DTSTART and DTEND are converted to UTC.
-		# UTC date/times work in all situations.
-
-		$utc_tz = new \DateTimeZone("UTC");
-
-		$cvt_dtstart = $start;
-		$cvt_dtstart_dt = $cvt_dtstart->getDateTime();
-		$dtstart_ts = $cvt_dtstart_dt->getTimestamp();
-		$cvt_dtstart_dt = new \DateTime("now", $utc_tz);
-		$cvt_dtstart_dt->setTimestamp($dtstart_ts);
-		$cvt_dtstart->setDateTime($cvt_dtstart_dt, false);
-
-		$cvt_dtend = $end;
-		$cvt_dtend_dt = $cvt_dtend->getDateTime();
-		$dtend_ts = $cvt_dtend_dt->getTimestamp();
-		$cvt_dtend_dt = new \DateTime("now", $utc_tz);
-		$cvt_dtend_dt->setTimestamp($dtend_ts);
-		$cvt_dtend->setDateTime($cvt_dtend_dt, false);
-
 		$itip_msg = $iTipMessage->message->serialize();
 		$message->addPart(
 				$itip_msg,