SLES15 SP4 | Installation of a rpm package fails when %post scriplet fails with "/usr/lib/1sb/install _initd: No such file or directory"

I have a .spec file to install a rpm. I have the following snippet in post install (%post scriplet)

%post -n %{package_name}
# Enable the service at boot time
%if %{?suse_version:1}0
  /usr/lib/lsb/install_initd %{_initrddir}/%{package_name}
%else
  chkconfig --add %{package_name}
%endi

During zypper install package_name it fails at the post installation phase with the following error:

/var/tmp/rpm-tmp.Z5R29N: line 2: /usr/lib/1sb/install _initd: No such file or directory
warning: %post (package_name.sles15.x86_64) scriptlet failed, exit status 127

I am a novice in .spec files for rpm but this scriplet failed because /usr/lib/lsb/ directory doesn't exists in SLES 15 SP4 My Questions are: 1. What is this scriplet exactly doing? 2. Where to get this /lsb/ package from so that I can create this path in SLES 15 SP4? I check that SLES 15 SP4 pre-installed with lsb-xxx package but they are not working here ? 3. Do I need to do case checks here for sles 15 SP4 inside this scriplet? like:

%if 0%{?sle_version} == 150400 && 0%{?is_opensuse}
// do somthing
%endif