Add the Chronological

vendor/sabre/vobject/lib/TimezoneGuesser/GuessFromLicEntry.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Sabre\VObject\TimezoneGuesser;
+
+use DateTimeZone;
+use Sabre\VObject\Component\VTimeZone;
+use Sabre\VObject\TimeZoneUtil;
+
+/**
+ * Some clients add 'X-LIC-LOCATION' with the olson name.
+ */
+class GuessFromLicEntry implements TimezoneGuesser
+{
+    public function guess(VTimeZone $vtimezone, bool $failIfUncertain = false): ?DateTimeZone
+    {
+        if (!isset($vtimezone->{'X-LIC-LOCATION'})) {
+            return null;
+        }
+
+        $lic = (string) $vtimezone->{'X-LIC-LOCATION'};
+
+        // Libical generators may specify strings like
+        // "SystemV/EST5EDT". For those we must remove the
+        // SystemV part.
+        if ('SystemV/' === substr($lic, 0, 8)) {
+            $lic = substr($lic, 8);
+        }
+
+        return TimeZoneUtil::getTimeZone($lic, null, $failIfUncertain);
+    }
+}