The self signed cert was generated something like so:
openssl genrsa -out server.key 2048
openssl req -new -x509 -sha256 -key server.key -out server.crt -days 3650
The cert, fakemail-publ-test-self-signed.crt, is placed here:
../app-dev/fakemail-publ-test-self-signed.crt, so it can be copied
into the app-dev Docker image, and added to the Java cert store [26UKWD2].