Our customers will refer to the below documentation when cinder uses multipath. 

4.5.2. Configuring custom multipath parameters on data plane nodes

However, no description about the `edpm_multipathd_custom_config_file` parameter which must be defined.
The important parameter due to below condition is defined in the task within edpm_multipathd role.
So if the parameter is empty, the below task will be skipped always and custom multipathd.conf won't be copied to data plane nodes.

https://github.com/openstack-k8s-operators/edpm-ansible/blob/main/roles/edpm_multipathd/tasks/configure.yml#L26-L32

    - name: Install custom multipath.conf if one is specified
      ansible.builtin.copy:
        src: "{{ edpm_multipathd_custom_config_dir }}/{{ edpm_multipathd_custom_config_file }}"
        dest: /etc/multipath.conf
        mode: "0644"
      when:
        - edpm_multipathd_custom_config_file|length > 0