Fix OpenNebula inventory crash when NIC does not have IP (#8489)

* Fix OpenNebula inventory crash when NIC does not have IP

Match IPv6 behaviour.

When a NIC does not have an IP:
  File "ansible/inventory/manager.py", line 292, in parse_source
    plugin.parse(self._inventory, self._loader, source, cache=cache)
  File "ansible-cm/plugins/inventory/opennebula.py", line 263, in parse
    self._populate()
  File "ansible-cm/plugins/inventory/opennebula.py", line 226, in _populate
    servers = self._retrieve_servers(filter_by_label)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "ansible-cm/plugins/inventory/opennebula.py", line 210, in _retrieve_servers
    server['v4_first_ip'] = self._get_vm_ipv4(vm)
                            ^^^^^^^^^^^^^^^^^^^^^
  File "ansible-cm/plugins/inventory/opennebula.py", line 154, in _get_vm_ipv4
    return net['IP']

* Update to call to match IPv6 and add changelog fragment

* Update changelog fragment.

---------

Co-authored-by: Felix Fontein <felix@fontein.de>

changelogs/fragments/8489-fix-opennebula-inventory-crash-when-nic-has-no-ip.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - opennebula inventory plugin - fix invalid reference to IP when inventory runs against NICs with no IPv4 address (https://github.com/ansible-collections/community.general/pull/8489).

plugins/inventory/opennebula.py

@@ -143,7 +143,8 @@ class InventoryModule(BaseInventoryPlugin, Constructable):
             nic = [nic]
 
         for net in nic:
-            return net['IP']
+            if net.get('IP'):
+                return net['IP']
 
         return False