Gets or sets the desired properties for the data source to load. If specified the data source may decide to constrain the properties it fetches to these properties and must make sure that at least those properties are loaded, rather than the default behavior for that data source.
Target Platforms: Android 4.4+, iOS 8+
Development Environments: Visual Studio 2015+, Visual Studio for Mac Preview, Xamarin for Visual Studio 4.2+
