presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/file/FileHiveMetastore.java/FileHiveMetastore/getPermissionsPath
class FileHiveMetastore:    private static Path getPermissionsPath(Path permissionsDirectory, HivePrincipal grantee)
    {
        return new Path(permissionsDirectory, grantee.getType().toString().toLowerCase(Locale.US) + "_" + grantee.getName());
    }