nextcloud/apps/files_sharing/appinfo/app.php

<?php

OC::$CLASSPATH['OC_Share'] = "apps/files_sharing/lib_share.php";
OC::$CLASSPATH['OC_Share_Backend_File'] = "apps/files_sharing/share.php";
OC::$CLASSPATH['OC_Filestorage_Shared'] = "apps/files_sharing/sharedstorage.php";

OCP\App::registerAdmin('files_sharing', 'settings');

OCP\Util::connectHook('OC_Filesystem', 'setup', 'OC_Filestorage_Shared', 'setup');

OCP\Util::connectHook("OC_Filesystem", "post_delete", "OC_Share", "deleteItem");
OCP\Util::connectHook("OC_Filesystem", "post_rename", "OC_Share", "renameItem");
OCP\Util::connectHook("OC_Filesystem", "post_write", "OC_Share", "updateItem");

OCP\Util::connectHook('OC_User', 'post_deleteUser', 'OC_Share', 'removeUser');
OCP\Util::connectHook('OC_User', 'post_addToGroup', 'OC_Share', 'addToGroupShare');
OCP\Util::connectHook('OC_User', 'post_removeFromGroup', 'OC_Share', 'removeFromGroupShare');

$dir = isset($_GET['dir']) ? $_GET['dir'] : '/';
if ($dir != '/Shared' || OCP\Config::getAppValue('files_sharing', 'resharing', 'yes') == 'yes') {
	OCP\Util::addScript('core', 'share');
}
OCP\Util::addscript("3rdparty", "chosen/chosen.jquery.min");
OCP\Util::addStyle( 'files_sharing', 'sharing' );
OCP\Util::addStyle("3rdparty", "chosen/chosen");
OCP\Share::registerBackend('file', new OC_Share_Backend_File());