Question

Is there a way to stop Hibernate from creating not-null constraints for properties annotated with @javax.validation.constraints.NotNull when using hbm2ddl = create?

Answer 1

From the documentation of Hibernate Validator:

6.1. Database schema-level validation

Out of the box, Hibernate Annotations
(as of Hibernate 3.5.x) will translate
the constraints you have defined for
your entities into mapping metadata.
For example, if a property of your
entity is annotated @NotNull, its
columns will be declared as not null
in the DDL schema generated by
Hibernate.

If, for some reason, the feature needs
to be disabled, set
hibernate.validator.apply_to_ddl to
false. See also Table 2.2, “Built-in
constraints”.

You can also limit the DDL constraint
generation to a subset of the defined
constraints by setting the property
org.hibernate.validator.group.ddl.
The property specifies the comma
seperated, fully specified classnames
of the groups a constraint has to be
part of in order to be considered for
DDL schema generation.

For more details about the org.hibernate.validator.group.ddl property, see also the section 4.1.2. Configuration.