For the maintainer, the general procedure differs from the C language case:
XGETTEXT_OPTIONS
variable in po/Makevars (see Makevars in po/) should be adjusted to
match the xgettext options for that particular programming language.
If the package uses more than one programming language with gettext
support, it becomes necessary to change the POT file construction rule
in po/Makefile.in.in. It is recommended to make one xgettext
invocation per programming language, each with the options appropriate for
that language, and to combine the resulting files using msgcat.