public static String logPre(ApplicationId app) {
        if (DEFAULT_TENANT.equals(app.tenant())) return "";
        return "app:" + app.toFullString() + " ";
    }
A helper to format a log preamble for messages with a tenant and app id

@param app the app
@return the log string
configserver/src/main/java/com/yahoo/vespa/config/server/tenant/TenantRepository.java