Objects without titles cannot be created via the Facebook Object API

Objects without titles cannot be created via the Facebook Object API

According to this document, the Open Graph API supports creating objects
without specifying the og:title property. I'm using the Object API, and
since the objects I'm defining don't have meaningful titles, I presumed
that I could do the same by just not including a 'title' field in my
request.
The request I'm sending (via the Graph API Explorer) is equivalent to this:
POST https://graph.facebook.com/me/objects/namespace:foo
object={
"image": "http://cdn.example.com/images/bar/l",
"url": "http://example.com/photos/baz?image=bar",
"description": "Image caption",
"site_name": "Example"
}
Except, the response I keep getting is:
{
"error": {
"message": "(#100) Object Missing a Required Value: Object at URL
'http://example.com/photos/baz?image=bar' of type 'namespace:foo' is
invalid because a required property 'og:title' of type 'string' was
not provided.",
"type": "OAuthException",
"code": 100
}
}
So, is it not possible at all to create objects without titles via the
Object API? Does this only apply to self-hosted objects?