JPA's @ManyToOne mapping fails when using Hibernate in conjunction with MySQL

This was reported by Ronald Vermeire in the Roo forums. Thanks Ronald!

The following script will fail on 'mvn test' with the following exception:

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Unsuccessful: create table product_group (id bigint not null auto_increment, version integer, index varchar(255), postfix bigint, prefix bigint, primary key (id))
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'varchar(255), postfix bigint, prefix bigint, primary key (id))' at line 1

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This might be a problem in Hibernate (generating an invalid SQL query or the MySQL driver itself.

The following script reproduces the issue:

create project -topLevelPackage com.foo
install jpa -database MYSQL -provider HIBERNATE
new persistent class jpa -name ~.Prefix -testAutomatically
add field string -fieldName name
new persistent class jpa -name ~.ProductGroup -testAutomatically
add field string -fieldName name
add field reference jpa -type com.foo.Prefix -fieldName prefix

However, changing the @ManyToOne mapping annotation in ProductGroup to have an explicit 'targetEntity' attribute fixes the issue:

@ManyToOne(targetEntity=Prefix.class)
@JoinColumn
private Prefix prefix;

So as a workaround we should include the targetEntity attribute by default.