Missing atto plugin unlink

line 103 of \lib\editor\atto\lib.php: call to debugging()
line 1355 of \lib\deprecatedlib.php: call to atto_texteditor->use_editor()
line 3988 of \lib\adminlib.php: call to print_textarea()
line 1490 of \lib\adminlib.php: call to admin_setting_special_frontpagedesc->output_html()
line 125 of \admin\settings.php: call to admin_settingpage->output_html()

It looks like the ATTO unlink plugin is missing from the /lib/editor/plugin/
was this an error or by design?