NPE in `HqlQueryTransformer.isSubquery` for INSERT from SELECT HQL

[kzander91]

With 3.1.0, repository initialization fails with

Caused by: java.lang.NullPointerException: Cannot invoke "org.antlr.v4.runtime.ParserRuleContext.getParent()" because "ctx" is null
	at org.springframework.data.jpa.repository.query.HqlQueryTransformer.isSubquery(HqlQueryTransformer.java:100) ~[spring-data-jpa-3.1.0.jar:3.1.0]

when declaring the following named query:

insert into MyEntity (id, col)
select max(id), col
from MyEntityStaging
group by col

Entities:

@Entity
@NamedQuery(name = "MyEntity.copyFromStaging", query = """
        insert into MyEntity (id, col)
        select max(id), col
        from MyEntityStaging
        group by col""")
class MyEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private Long id;
    private String col;
}

@Entity
class MyEntityStaging {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private Long id;
    private String col;
}

Repository:

interface MyEntityRepository extends JpaRepository<MyEntity, Long> {
    @Modifying
    @Transactional
    void copyFromStaging();
}

Reproducer:
demo.zip
Extract and run ./mvnw spring-boot:run to observe the exception.
In the pom.xml, change the spring-data-jpa.version from 3.1.0 to 3.0.6 and run again, now it works.

[gregturn]

I've reproduced the same thing using:

	@Test // GH-2977
	void isSubqueryThrowsException() {

		String query = """
				insert into MyEntity (id, col)
				select max(id), col
				from MyEntityStaging
				group by col
				""";

		assertThat(createQueryFor(query, Sort.unsorted())).isEqualTo(query);
	}

This reason this works with Spring Data JPA 3.0 is we didn't introduce the HQL parser until 3.1, so that switches to the old way.

[gregturn]

That's merged to main and backported to 3.1.x.

[kzander91]

That was fast, thanks a lot :)