Common project settings
If you have a set of configuration properties you want for all your projects, you can create a common .props file that will automatically be picked up and used. All you need is a file called the same as the project with a .props extension. In our case, the project name is Roslyn.Extensions, so the file needed would be called Roslyn.Extensions.props.
A props file is basically just an MSBuild project file as the .csproj file. MSBuild has a convention of automatically importing this file from a common extension project like this into consumers of the extension package.
Within a common project settings file, you can do more than just add properties. You can include files, add package references, or do anything that you can do in a regular .csproj file. That is super powerful when you want to apply and enforce common settings.
Add a file called Roslyn.Extensions.props to the Roslyn.Extensions project and put the following code into it:
<Project>...
