We are currently in the process of switching the default firewall from
SuSEfirewall2 to firewalld for SLE-15 and Leap-15. firewalld ships a
bulk of predefined network services already. The icecream ports are not
covered by that, however.

Since these are special ports not assigned by IANA I suggest you add a
custom firewalld XML service file to your package.

There are some instructions on how to do this here:

https://en.opensuse.org/Firewalld/RPM_Packaging

You can/should keep the SuSEfirewall2 service file in the package (for
Factory/Tumbleweed) to keep it working until we decide to completely drop it.

Thank you.