presto-main/src/main/java/io/prestosql/security/AccessControlManager.java/AccessControlManager/loadSystemAccessControl
class AccessControlManager:    public void loadSystemAccessControl()
            throws Exception
    {
        log.info("-- Loading system access control --");

        File configFile = CONFIG_FILE.getAbsoluteFile();
        if (!configFile.exists()) {
            setSystemAccessControl(AllowAllSystemAccessControl.NAME, ImmutableMap.of());
            log.info("-- Loaded system access control %s --", AllowAllSystemAccessControl.NAME);
            return;
        }

        Map<String, String> properties = new HashMap<>(loadProperties(configFile));

        String name = properties.remove(NAME_PROPERTY);
        checkState(!isNullOrEmpty(name), "Access control configuration %s does not contain '%s'", configFile, NAME_PROPERTY);

        setSystemAccessControl(name, properties);
        log.info("-- Loaded system access control %s --", name);
    }