How can in house developed Eclipse plugins be used in Maven projects?

I have some experience with Eclipse IDE. I have several projects written with headless-RCP back from Oxygen 3.8. I want to convert or re-write them into Maven projects.

My headless-RCP projects use plugins I have developed in Eclipse. The Eclipse plugins were developed as separate projects.

For example, I have a headless RCP project which runs entirely in console mode. It is support by connection and image plugins I have developed.

How could I re-use these inhouse plugins when re-writing or converting my application to Maven?

I am just now getting started in M2E, Maven in Eclipse. I am researching this questions. I haven’t found anything in Google about how to use an Eclipse plugin in a Maven project.