In order to automate maintenance of copyright headers in our source
code (especially when merging PRs from external contributors), this
commit introduces an update_copyright_headers.sh script (tested on
mac OS) that will update the copyright headers of all Java, Kotlin,
and Groovy source files that have been added or modified this year
(or at least as far back as the git log history supports it).
For example, running this script currently outputs the following.
Updating copyright headers in Java, Kotlin, and Groovy source code for year 2022
warning: log for 'main' only goes back to Tue, 16 Aug 2022 16:24:55 +0200
Sam Brannen