Porting Code from 3rd Party Sources

When porting code or adapting code from other projects with a MIT compatible license, the source file must contain appropriate license headers. For example when porting code from WPF the header should contain:

// This source file is adapted from the Windows Presentation Foundation project. 
// (https://github.com/dotnet/wpf/) 
// 
// Licensed to The Avalonia Project under MIT License, courtesy of The .NET Foundation.

If the file is a port of a specific commit of file from a 3rd party source, then consider including a permalink to the source file.