Dictionary of dictionary isn't supported

[czf]

is this intentional?

Here is an over simplified example
typeof(Dictionary<int,Dictionary<int,int>>).GetSchema()
results in

'typeof(Dictionary<int,Dictionary<int,int>>).GetSchema()' threw an exception of type 'System.ArgumentException'
Data: {System.Collections.ListDictionaryInternal}
HResult: -2147024809
HelpLink: null
InnerException: null
Message: "Dictionary`2 not supported"