When I try to install the stunnel into the SUSE linux, I got the below response information:

bash-4.4# zypper install -l -y stunnel
Loading repository data...
Reading installed packages...
Resolving package dependencies...

Problem: nothing provides group(nogroup) needed by stunnel-5.49-37.14.x86_64
Solution 1: do not install stunnel-5.49-37.14.x86_64
Solution 2: break stunnel-5.49-37.14.x86_64 by ignoring some of its dependencies

Choose from above solutions by number or cancel [1/2/c] (c): c

anyone can tell me the problem "nothing provides group(nogroup)" means exactly what? how to fix?
I have tried to add nogroup by command "groupadd nogroup", seems not help.