AutoCAD .NET :: Reading XREF Tree From External Exe

I am trying to read the xref tree from a DWG by using an external exe. The app should simply open the DWG and sys-out the referenced paths and whether or not they are nested. For this, I am using Autodesk.AutoCAD.Interop. The problem is that I can only get a list of file dependencies (document.FileDependencies) and I can't seem to find an "isNested" value.

So far I've got:

AcadDocument document = oAcadApp.Documents.Open("Test.dwg");
foreach (AcadFileDependency o in document.FileDependencies)
{
System.Console.Out.WriteLine(o.FullFileName);
}

There is also the option to get Blocks, but again there is no "isNested" info, only "isXref":
foreach (AcadBlock b in document.Database.Blocks)

{
if (b.IsXRef)
{
...doStuff...
}
}