presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/file/FileHiveMetastore.java/FileHiveMetastore/getAllDatabases
class FileHiveMetastore:    @Override
    public synchronized List<String> getAllDatabases()
    {
        List<String> databases = getChildSchemaDirectories(catalogDirectory).stream()
                .map(Path::getName)
                .collect(toList());
        return ImmutableList.copyOf(databases);
    }