presto-hive/src/main/java/io/prestosql/plugin/hive/util/HiveBucketingV1.java/HiveBucketingV1/hashOfMap
class HiveBucketingV1:    private static int hashOfMap(MapTypeInfo type, Block singleMapBlock)
    {
        TypeInfo keyTypeInfo = type.getMapKeyTypeInfo();
        TypeInfo valueTypeInfo = type.getMapValueTypeInfo();
        int result = 0;
        for (int i = 0; i < singleMapBlock.getPositionCount(); i += 2) {
            result += hash(keyTypeInfo, singleMapBlock, i) ^ hash(valueTypeInfo, singleMapBlock, i + 1);
        }
        return result;
    }