$build['flexible_event_calendar'] = [ '#data' => [ 'events' => [ [ 'id' => '111' , 'name' => 'New Year', 'date' => "January/1/2020", 'type' => "event" ], [ 'id' => '111' , 'name' => 'Organization Meeting', 'date' => "January/1/2020", 'type' => "event" ], [ 'id' => '222' , 'name' => 'Board Meeting', 'date' => "January/31/2020", 'type' => "event" ], ], ], '#type' => 'flexible_event_calendar' ];