春联盟JPA或规范

Question

尝试为以下查询创建条件构建器。但是，JPA似乎不支持UNION。有什么想法吗？

SELECT * 
FROM   firsttable i1 
WHERE  EXISTS (SELECT 1 
               FROM   secondtable 
               WHERE  id = i1.fid 
                      AND flag = 'Flag1') 
       AND EXISTS (SELECT 1 
               FROM   secondtable 
               WHERE  id = i1.fid 
                      AND flag = 'Flag2') 

UNION 

SELECT * 
FROM   firsttable i1 
WHERE  NOT EXISTS (SELECT 1 
               FROM   secondtable 
               WHERE  id = i1.fid 
                      AND flag = 'Flag1') 
       AND EXISTS (SELECT 1 
               FROM   secondtable 
               WHERE  id = i1.fid 
                      AND flag = 'Flag2');