@Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("application '").append(app.application().value()).append("', ");
        sb.append("generation ").append(applicationGeneration).append(", ");
        sb.append("vespa version ").append(vespaVersion);
        return sb.toString();
    }
Returns the application model, never null
configserver/src/main/java/com/yahoo/vespa/config/server/application/Application.java