Category "many-to-one"

Error executing DDL "alter table add constraint foreign key () references (id)" via JDBC Statement

Error executing DDL "alter table child add constraint foreign key (parent_id) references (id)" via JDBC Statement caused by Failed to add the foreign key c

JPA CriteriaBuilder ManyToOne and null values

I'm trying to create a Specification for filtering a table. This table has 2 @ManyToOne relationships (that can be null) and I'd like to apply the filter inside