What is the correct syntax for UnityEditor.VersionControl.Provider.GetAssetByPath?

I tried the following as a test,

        if (!Provider.enabled || !Provider.isActive) { return false; }

        var asset = Provider.GetAssetByPath(Path.GetFullPath(Application.dataPath));

yet asset is always null.

This logic is in a function that is being called from a MenuItem so it is running in the context of the UnityEditor (not in play mode). The path returned from Path.GetFullPath(Application.dataPath) looks perfectly valid.

I am on Windows 10, using Unity 5.2.3f1. Version Control is Perforce.

According to the Provider.GetAssetByPath documentation:

Returns null if the path is not known
by the Unity Editor.

It seems likely that only assets within the project folder and below would be “known” to the editor. You’re trying to get version control information for an object that isn’t in the project folder.