List<String> topics = entityManager.createQuery("""
	(
		select c.name as name
		from Category c
		order by c.id
	)
	union
	(
		select t.name as name
		from Tag t
		order by t.id
	)
	""", String.class)
.getResultList();

n.t.d.l.l.SLF4JQueryLoggingListener - Name:DATA_SOURCE_PROXY, Connection:6, Time:20, Success:False, Type:Prepared, Batch:False, QuerySize:1, BatchSize:0, Query:["select c1_0.name from category c1_0 order by c1_0.id union select t1_0.name from tag t1_0 order by t1_0.id"], Params:[()]
o.h.e.j.s.SqlExceptionHelper - SQL Error: 0, SQLState: 42601
o.h.e.j.s.SqlExceptionHelper - ERROR: syntax error at or near "union"

select c1_0.name from category c1_0 order by c1_0.id 
union 
select t1_0.name from tag t1_0 order by t1_0.id

(select c1_0.name from category c1_0 order by c1_0.id)
union
(select t1_0.name from tag t1_0 order by t1_0.id)