private Level calcLogLevel() {
        switch (getVerbosity().length) {
            case 0:  return Level.WARN;
            case 1:  return Level.INFO;
            case 2:  return Level.DEBUG;
            default: return Level.TRACE;
        }
    }
Taken from https://github.com/remkop/picocli/blob/master/picocli-examples/src/main/java/picocli/examples/logging_mixin_advanced/LoggingMixin.java
migration-assistant/src/main/java/io/apiman/migration/util/LoggingMixin.java