It seems like 3.1.4 is a broken release, as the JettyConnectorProvider always throws an exception:
@Override
public Connector getConnector(Client client, Configuration runtimeConfig) {
throw new ProcessingException(LocalizationMessages.NOT_SUPPORTED());
}
}
I'm going to take a wild guess and say that you probably meant to include a non-exception-throwing version under META-INF/versions/17, but there is no such class. So, the connector simply doesn't work at the moment.