2b949de8e9
Sometimes, especially in places like service-to-service defaults, it's very helpful to express a list of values. For instance, when thinking about nova connecting to ironic, nova would like to have the default value of "interface" be ['internal', 'public'] - which is to say, use internal if it's there, but otherwise use public. This use case is covered in the API-WG specs on discoverability. Change-Id: I9102155c2d4ef1ef8bbb1d0fa26a5b5838108a4c