The package contains a private, portable (by 'portable' I mean .NET, .NET Standard, or .NET Core) build of the .NET pluralization service in the System.Data.Entity.Design assembly.
All the code was found here: https://github.com/Microsoft/referencesource/tree/master/System.Data.Entity.Design/System/Data/Entity/Design/PluralizationService
All the code is Copyright (c) Microsoft Corporation. All rights reserved.
The code is licensed under the MIT license.
I created this assembly because I needed a pluralization service that would behave in a predictable manner and work with whatever platform/version I was targeting.