We are trying to migrate a project from hibernate 3 to hibernate 5. We have a legacy database that contains composite foreign key referencing non primary keys. To best explain the problem, I take the example from http://learningviacode.blogspot.com/201 ... ncing.html

Here is the mapping file:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.ec.composite_foreign_non_primary">
<class name="Student" table="STUDENT">
<id name="id" type="integer" column="ID">
<generator class="native" />
</id>
<properties name="StudentKey" unique="true">
<property name="name" column="STUDENT_NAME" />
<property name="schoolName" column="SCHOOL_NAME" />
</properties>
<set name="vehicles" cascade="all" inverse="true">
<key property-ref="StudentKey" >
<column name="STUDENT_NAME"/>
<column name="SCHOOL_NAME"/>
</key>
<one-to-many class="Vehicle" />
</set>
</class>
</hibernate-mapping>

It works with Hibernate 3.3. With hibernate 5, it complains StudentKey not found.

Stack Trace:
Caused by: org.hibernate.MappingException: property [StudentKey] not found on entity [com.ec.composite_foreign_non_primary.Student]
at org.hibernate.mapping.PersistentClass.getRecursiveProperty(PersistentClass.java:425)
at org.hibernate.boot.model.source.internal.hbm.ModelBinder$AbstractPluralAttributeSecondPass.bindCollectionKey(ModelBinder.java:3266)
at org.hibernate.boot.model.source.internal.hbm.ModelBinder$AbstractPluralAttributeSecondPass.doSecondPass(ModelBinder.java:3086)
at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1621)
at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1589)
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:278)
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:83)
at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:418)
at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:87)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:692)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:724)

Does Hibernate 5 support at all this kind of mapping for legacy database? Your insight will be appreciated.

It supports Composite Keys and more advanced mappings than 3.3. What you might want to try is to use Annotations for the entities with Composite Keys, as explained in this blog post. Annotations are better supported in 5.x than legacy HBM mappings.