This is a customization of System.ComponentModel.Annotations. Sources have been forked from https://github.com/dotnet/corefx/releases/tag/v1.1.8 then customized by Ole Consignado in order to meet it needs.

Original sources should be found at: https://github.com/dotnet/corefx/tree/v1.1.8/src/System.ComponentModel.Annotations

Thanks to Microsoft for making it open source!