Best practice for .net solution containing multiple projects with common middleware folders

[michel18]

I have a .net core solution containing 3 projects(Apis for the mobile app, for the website and CMS) and all of these projects use the same middlewares inside a common folder that exists outside the 3 projects.

What are the solutions to create repositories with the ability to adapt to a CI/CD noting that each project should be transformed to a docker image including the common folder.

I know  that i can have 3 solutions and copy paste the common folder inside all 3 solutions but i am looking for something more proper.