/lib/partman/active_partition/45xfs/choices is in ubiquity 2.18.7.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 | #!/bin/sh
. /usr/share/debconf/confmodule
set -e
dev=$1
id=$2
part=$dev/$id
cd $dev
[ -f $part/method -a -f $part/acting_filesystem ] || exit 0
filesystem=$(cat $part/acting_filesystem)
case "$filesystem" in
    xfs)
	:
	;;
    *)
	exit 0
	;;
esac
choice_mountpoint () {
	case "$filesystem" in
	    xfs)
		if [ -f $part/mountpoint ]; then
			mp=$(cat $part/mountpoint)
		else
			db_metaget partman-basicfilesystems/text/no_mountpoint description
			mp="$RET"
		fi
		db_metaget partman-basicfilesystems/text/specify_mountpoint description
		printf "mountpoint\t%s\${!TAB}%s\n" "$RET" "$mp"
		;;
	esac
}
choice_options () {
	db_metaget partman-basicfilesystems/text/options description
	printf "options\t%s\${!TAB}%.45s\n" "$RET" "$(get_mountoptions $dev $id)"
}
choice_label () {
	# allow to set label only if the partition is to be formatted
	[ -f $part/format ] || return 0
	[ ! -f $part/formatted \
	  -o $part/formatted -ot $part/method \
	  -o $part/formatted -ot $part/filesystem ] || return 0
	case "$filesystem" in
	    xfs)
		if [ -f $part/label ]; then
			label=$(cat $part/label)
		else
			db_metaget partman-basicfilesystems/text/none description
			label=$RET
		fi
		db_metaget partman-basicfilesystems/text/specify_label description
		printf "label\t%s\${!TAB}%s\n" "$RET" "$label"
		;;
	esac
}
choice_mountpoint
choice_options
choice_label
 |