service module with systemd and support for arguments parameter

$ ansible --version
ansible 2.3.1.0
  config file = /etc/ansible/ansible.cfg
  configured module search path = Default w/o overrides
  python version = 2.7.14 (default, Oct 2 2017, 09:52:26) [GCC 4.2.1
Compatible OpenBSD Clang 4.0.0 (tags/RELEASE_400/final)]

I'm working on a role to manage NTP client setup on target hosts and
am confused about how to handle something. On recent Debian Linux
hosts, systemd is the service manager. I want to run the OpenNTPD
daemon with the "-s" argument, so in the task I add it in the
arguments parameter as shown below:

- name: enable ntp service
  service:
    name: '{{ ntpd_service_name }}'
    enabled: '{{ ntpd_service_enabled }}'
    state: '{{ ntpd_service_state }}'
    arguments: '{% if ntpd_step_time %}-s{%endif %}'
    use: '{{ ntpd_service_mgr }}'
  tags: [ntp]

When the task runs it notes that systemd does not use the arguments parameter:

TASK [ntp_client : enable ntp service]