The source tarballs of nfs-utils (2.3.3, 2.4.1) contain a file './support/nfsidmap/idmapd.conf'. It's a default configuration file for libnfsidmap and it should be installed to /etc/idmapd.conf.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=f776b0a27871c309966369488fefc441e72ac4fc commit f776b0a27871c309966369488fefc441e72ac4fc Author: Matt Turner <mattst88@gentoo.org> AuthorDate: 2019-09-02 07:05:17 +0000 Commit: Matt Turner <mattst88@gentoo.org> CommitDate: 2019-09-02 07:08:13 +0000 net-fs/nfs-utils: Install idmapd.conf Closes: https://bugs.gentoo.org/690982 Signed-off-by: Matt Turner <mattst88@gentoo.org> net-fs/nfs-utils/nfs-utils-2.4.1.ebuild | 3 +++ 1 file changed, 3 insertions(+)