hook_libraries_info() broken with xautoload 5.x

Enabling xautoload with this module enabled causes exception:

exception 'Exception' with message 'Serialization of 'Closure' is not allowed' in sites/all/modules/contrib/xautoload/src/Libraries/LibrariesFinderPlugin.php:108

In hook_libraries_info() you make a call to \Drupal\xautoload\Adapter\LocalDirectoryAdapter::namespaceRoot() which no longer exists.

Deleting the xautoload key prevents the error.