I am involved in an open-source project with multiple copyright holders. The project is licensed under the 3-clause BSD license. Unfortunately, the individual code files contain no reference back to their original owners (no copyright headers), but for the project as a whole a single file LICENSE.txt, which contains the BSD license text, is provided. The project also contains a separate file which identifies all copyright holders.
However, I am struggling with a pragmatic question: the first line of the BSD license is supposed to identify the copyright owner:
Copyright (c) <year>, <copyright holder>
In our case, there is no single copyright owner (at least not for the project as a whole). So what should I put here, practically speaking? Obviously I can't just leave it out as the license itself refers to retaining "the above copyright notice". Is there a recommended way / format to list all copyright holders here, or perhaps to refer to an external list of copyright holders? We are talking 10 or more contributors by the way, some of them individuals, some companies, so it's not a short list.
I looked at how some other projects do this (e.g. Linux), but most I could find use GPL, which does not contain the
<copyright owner> bit in the license - and I have sofar failed to find a project that uses BSD and has multiple owners.