capture.device.names not properly set if there is only one properties-response.properties.item

[felix-itz]

Version
Which plugin version are you using exactly?

Version 2.MLU. However, looking at the code, at a first glace, it looks the same. Maybe someone with V3 and a capture agent with exactly one properties-response.properties.item for https://admin-server/capture-admin/agents/capture-agent-name/capabilities.json can confirm?

Describe the bug
A clear and concise description of what the bug is.

When there is exactly one properties-response.properties.item in response to https://admin-server/capture-admin/agents/capture-agent-name/capabilities.json, Opencast returns an Object, not an array, which the plugin receives and the plugin won't set any capture.device.names when scheduling an event.

To Reproduce
Steps to reproduce the behavior:

1. Have a capture agent that adds exactly one capability to Opencast and that refuses to record if it gets no capture.device.names.
2. Configure the Stud.IP Opencast Plugin to use the Opencast instance.
3. Configure the Stud.IP Opencast Plugin to assign the capture agent to a room.
4. Create a date in a course and book the room the capture agent was assigned to.
5. Enable Opencast, Accept ToS, and Schedule a recording.
6. When the event is due for recording, nothing happens, although Opencast displays the event.

On our new shiny Epiphan Pearl2 Recorders, this is what they log:

Channel '' is not available and will be ignored for the event b7d8682c-e0fa-4fcc-9bfc-3e890c569325
Cannot process event b7d8682c-e0fa-4fcc-9bfc-3e890c569325: Event does not have any channel. Skipped

Scheduled event in Opencast 14:

Recorder caps in Opencast 14:

Expected behavior
All capture.device.names set. See also #1411