presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/file/FileHiveMetastore.java/FileHiveMetastore/readAllPermissions
class FileHiveMetastore:    private Set<HivePrivilegeInfo> readAllPermissions(Path permissionsDirectory)
    {
        try {
            return Arrays.stream(metadataFileSystem.listStatus(permissionsDirectory))
                    .filter(FileStatus::isFile)
                    .filter(file -> !file.getPath().getName().startsWith("."))
                    .flatMap(file -> readPermissionsFile(file.getPath()).stream())
                    .collect(toImmutableSet());
        }
        catch (IOException e) {
            throw new PrestoException(HIVE_METASTORE_ERROR, e);
        }
    }