fix(share): use share owner to get ownership

Signed-off-by: Maxence Lange <maxence@artificial-owl.com>

lib/private/Share20/Manager.php

@@ -297,7 +297,7 @@ protected function generalCreateChecks(IShare $share) {
 		$isFederatedShare = $share->getNode()->getStorage()->instanceOfStorage('\OCA\Files_Sharing\External\Storage');
 		$permissions = 0;
 
-		if (!$isFederatedShare && $share->getNode()->getOwner() && $share->getNode()->getOwner()->getUID() !== $share->getSharedBy()) {
+		if (!$isFederatedShare && $share->getShareOwner() !== $share->getSharedBy()) {
 			$userMounts = array_filter($userFolder->getById($share->getNode()->getId()), function ($mount) {
 				// We need to filter since there might be other mountpoints that contain the file
 				// e.g. if the user has access to the same external storage that the file is originating from