presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/RaptorTableProperties.java/RaptorTableProperties/getBucketColumns
class RaptorTableProperties:    public static List<String> getBucketColumns(Map<String, Object> tableProperties)
    {
        return stringList(tableProperties.get(BUCKETED_ON_PROPERTY));
    }