MacOS High Sierra FakeSMTP Exception thrown NoClassDefFoundError

[hjmf1954]

I am trying to run FakeSMTP on MacOS High Sierra with installed MAMP Pro.
When I run the FakeSMTP server (port 2525) and the integration test I receive the following error:

Exception: java.lang.NoClassDefFoundError thrown from the UncaughtExceptionHandler in thread "org.subethamail.smtp.server.ServerThread *:2525"

I have update my java JSD and SE from 1.8.0_25 to 9.0.1+11 without any other outcome than the above given exception.

Also I get the following error in the mvn integration test:
DEBUG SMTP: useEhlo true, useAuth false
DEBUG SMTP: trying to connect to host "localhost", port 2525, isSSL false
DEBUG SMTP: exception reading response: java.net.SocketTimeoutException: Read timed out

It makes no difference to run with or without MAMP(Pro).