##### SUMMARY
When specifying only action name and state "absent", that fails with "missing required arguments: event_source".
Zabbix action names are unique across types (event sources), thus the event source parameter in this case is not mandated by the Zabbix API.
It would be great to either lift this limitation, or add an example in the documentation explaining why it's there.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
zabbix_action

##### ANSIBLE VERSION
latest

##### CONFIGURATION
Not relevant.

##### OS / ENVIRONMENT
Not relevant.

##### STEPS TO REPRODUCE

```yaml
  - name: "Report problems to Zabbix administrators"
    state: absent
```

##### EXPECTED RESULTS
Either success, or documented special limitation.

##### ACTUAL RESULTS
```
failed: [host] (item={u'state': u'absent', u'name': u'Report problems to Zabbix administrators'}) => {"ansible_loop_var": "item", "changed": false, "item": {"name": "Report problems to Zabbix administrators", "state": "absent"}, "msg": "missing required arguments: event_source"}
```
- Defaults to C(custom_expression) when formula is specified.
        choices:
            - 'andor'
            - 'and'
            - 'or'
            - 'custom_expression'
    formula:
        description:
            - User-defined expression to be used for evaluating conditions of filters with a custom expression.
            - The expression must contain IDs that reference specific filter conditions by its formulaid.
            - The IDs used in the expression must exactly match the ones
              defined in the filter conditions. No condition can remain unused or omitted.
            - Required for custom expression filters.
            - Use sequential IDs that start at "A". If non-sequential IDs are used, Zabbix re-indexes them.
              This makes each module run notice the difference in IDs and update the action.
    default_message:
        description:
            - Problem message default text.
    default_subject:
        description:
            - Problem message default subject.
    recovery_default_message:
        description:
            - Recovery message text.
            - Works only with >= Zabbix 3.2
    recovery_default_subject:
        description:
            - Recovery message subject.
            - Works only with >= Zabbix 3.2
    acknowledge_default_message: