//serialized data from v2
$data = 'O:19:"Carbon\CarbonPeriod":24:{s:12:" * dateClass";s:13:"Carbon\Carbon";s:15:" * dateInterval";O:21:"Carbon\CarbonInterval":22:{s:1:"y";i:0;s:1:"m";i:0;s:1:"d";i:3;s:1:"h";i:0;s:1:"i";i:0;s:1:"s";i:0;s:1:"f";d:0;s:6:"invert";i:0;s:4:"days";b:0;s:11:"from_string";b:0;s:9:" * tzName";N;s:7:" * step";N;s:22:" * localMonthsOverflow";N;s:21:" * localYearsOverflow";N;s:25:" * localStrictModeEnabled";N;s:24:" * localHumanDiffOptions";N;s:22:" * localToStringFormat";N;s:18:" * localSerializer";N;s:14:" * localMacros";N;s:21:" * localGenericMacros";N;s:22:" * localFormatFunction";N;s:18:" * localTranslator";N;}s:14:" * constructed";b:1;s:20:" * isDefaultInterval";b:0;s:10:" * filters";a:1:{i:0;a:2:{i:0;a:2:{i:0;s:19:"Carbon\CarbonPeriod";i:1;s:13:"filterEndDate";}i:1;N;}}s:12:" * startDate";O:13:"Carbon\Carbon":3:{s:4:"date";s:26:"2018-04-21 00:00:00.000000";s:13:"timezone_type";i:3;s:8:"timezone";s:3:"UTC";}s:10:" * endDate";O:13:"Carbon\Carbon":3:{s:4:"date";s:26:"2018-04-27 00:00:00.000000";s:13:"timezone_type";i:3;s:8:"timezone";s:3:"UTC";}s:14:" * recurrences";N;s:10:" * options";i:0;s:6:" * key";N;s:10:" * current";N;s:11:" * timezone";N;s:19:" * validationResult";N;s:9:" * tzName";N;s:22:" * localMonthsOverflow";N;s:21:" * localYearsOverflow";N;s:25:" * localStrictModeEnabled";N;s:24:" * localHumanDiffOptions";N;s:22:" * localToStringFormat";N;s:18:" * localSerializer";N;s:14:" * localMacros";N;s:21:" * localGenericMacros";N;s:22:" * localFormatFunction";N;s:18:" * localTranslator";N;}';

$period = unserialize($data);