Для Tumbleweed запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/home:fmccarthy:AI:pulsar:java/Tumbleweed/home:fmccarthy:AI:pulsar:java.repo
zypper refresh
zypper install jnr-ffi
Для 15.6 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/home:fmccarthy:AI:pulsar:java/15.6/home:fmccarthy:AI:pulsar:java.repo
zypper refresh
zypper install jnr-ffi
Для 15.4 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/home:fmccarthy:AI:pulsar:java/15.4/home:fmccarthy:AI:pulsar:java.repo
zypper refresh
zypper install jnr-ffi