There is an opensource project that I started some years ago and I still maintain it. This project is licensed under the BSD (3 clause) license and at the moment I am the sole copyright holder and contributor of the project.
Every source file contains this copyright info:
// Copyright (C) 2009-2016, <my name>.
// All rights reserved.
// Code licensed under the BSD License.
// http://www.<projects_website>.org/LICENSE
Here is a link to the BSD license.
Recently someone expressed his interest in contributing and I would like to know what is the best way to handle contributions so that everyone is happy. Copyright transfer agreement? Adding new copyright co-owners in files. Something else? What kind of changes I'll need to make to the license and the source files' copyright notice?