/usr/share/ltsp/plugins/ltsp-build-client/Gentoo/ is in ltsp-server 5.5.1-1ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/share/ltsp/plugins/ltsp-build-client/Gentoo/000-basic-configuration
/usr/share/ltsp/plugins/ltsp-build-client/Gentoo/001-set-arch
/usr/share/ltsp/plugins/ltsp-build-client/Gentoo/002-set-stage-file
/usr/share/ltsp/plugins/ltsp-build-client/Gentoo/010-bootstrap
/usr/share/ltsp/plugins/ltsp-build-client/Gentoo/010-serial-console
/usr/share/ltsp/plugins/ltsp-build-client/Gentoo/020-rootpath
/usr/share/ltsp/plugins/ltsp-build-client/Gentoo/020-set-initramfs-options
/usr/share/ltsp/plugins/ltsp-build-client/Gentoo/020-set-kernel-options
/usr/share/ltsp/plugins/ltsp-build-client/Gentoo/030-set-input-devices
/usr/share/ltsp/plugins/ltsp-build-client/Gentoo/030-set-video-cards
/usr/share/ltsp/plugins/ltsp-build-client/Gentoo/040-update-sshkeys
/usr/share/ltsp/plugins/ltsp-build-client/Gentoo/095-exports