Message Title

Classifying this as a bug because it effectively prevents from using Hibernate ORM in a modular environment beyond the very simple use cases, even though we did some work to make Hibernate ORM usable, as an automatic module.

In short, when a user deploys an application in the module path, they have no choice but to only ever use modules. As a result, they will use Hibernate ORM as an automatic module, and more importantly they will also use other libraries, such as Hibernate Search, as automatic modules. They simply cannot leave those in the classpath: they couldn't access them.

The problem is, as soon as other libraries are in the module path, Hibernate ORM seems unable to detect their declared services.

I investigated a bit, and the problem is not that automatic modules cannot declare services or use services from other modules (that works just fine), it's really only Hibernate ORM that fails to load the modules. You can see this live in this reproducer: https://github.com/yrodiere/java-module-sandbox/

     [exec] ======================================================
     [exec]                   STARTING EXECUTION                  
     [exec] ======================================================
     [exec] 
     [exec] 
     [exec] module { name: org.hibernate.sandbox.java.service.provider@1.0-SNAPSHOT, [mandated java.base], provides: [org.hibernate.sandbox.java.service.consumer.MyService with [org.hibernate.sandbox.java.service.provider.MyServiceImpl]] }
     [exec] module { name: org.hibernate.search.util.common@6.0.0-SNAPSHOT, [mandated java.base] }
     [exec] module { name: org.hibernate.search.mapper.pojo@6.0.0-SNAPSHOT, [mandated java.base] }
     [exec] module { name: org.hibernate.search.engine@6.0.0-SNAPSHOT, [mandated java.base] }
     [exec] module { name: org.hibernate.sandbox.java.main@1.0-SNAPSHOT, [org.hibernate.orm.core, org.hibernate.search.mapper.orm, mandated java.base (@11.0.3), net.bytebuddy, java.xml.bind, java.sql (@11.0.3), java.naming (@11.0.3), h2, org.hibernate.sandbox.java.service.consumer], exports: [org.hibernate.sandbox.java.main] }
     [exec] module { name: org.hibernate.search.mapper.orm@6.0.0-SNAPSHOT, [mandated java.base], provides: [org.hibernate.service.spi.ServiceContributor with [org.hibernate.search.mapper.orm.impl.HibernateSearchContextServiceContributor], org.hibernate.integrator.spi.Integrator with [org.hibernate.search.mapper.orm.bootstrap.impl.HibernateSearchIntegrator]] }
     [exec] module { name: org.hibernate.orm.core@5.4.2.Final, [mandated java.base], provides: [javax.persistence.spi.PersistenceProvider with [org.hibernate.jpa.HibernatePersistenceProvider]] }
     [exec] module { name: org.hibernate.commons.annotations@5.1.0.Final, [mandated java.base] }
     [exec] module { name: org.hibernate.sandbox.java.service.consumer@1.0-SNAPSHOT, [mandated java.base] }
     [exec] 
     [exec] 
     [exec] ===== RESULT:
     [exec] My services loaded from consumer module (automatic module without module-info.java): 
     [exec] [org.hibernate.sandbox.java.service.provider.MyServiceImpl]
     [exec] 
     [exec] 
     [exec] ===== RESULT:
     [exec] Hibernate ORM services loaded from consumer module (automatic module without module-info.java): 
     [exec] [org.hibernate.search.mapper.orm.bootstrap.impl.HibernateSearchIntegrator@5f3a4b84, org.hibernate.search.mapper.orm.impl.HibernateSearchContextServiceContributor@27f723]
     [exec] 
     [exec] 
     [exec] Booting Hibernate ORM service registry...
     [exec] May 23, 2019 10:05:17 AM org.hibernate.Version logVersion
     [exec] INFO: HHH000412: Hibernate Core {[WORKING]}
     [exec] Finished booting Hibernate ORM service registry.
     [exec] 
     [exec] 
     [exec] ===== RESULT:
     [exec] Hibernate services loaded from Hibernate ORM module by bootstrapping a service registry only: 
     [exec] [org.hibernate.cfg.beanvalidation.BeanValidationIntegrator@22eeefeb, org.hibernate.secure.spi.JaccIntegrator@64485a47, org.hibernate.cache.internal.CollectionCacheInvalidator@77846d2c]
     [exec] 
     [exec] 
     [exec] Booting Hibernate ORM session factory...
     [exec] May 23, 2019 10:05:17 AM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit>
     [exec] INFO: HCANN000001: Hibernate Commons Annotations {5.1.0.Final}
     [exec] May 23, 2019 10:05:17 AM org.hibernate.engine.jdbc.connections.internal.ConnectionProviderInitiator initiateService
     [exec] WARN: HHH000181: No appropriate connection provider encountered, assuming application will be supplying connections
     [exec] May 23, 2019 10:05:17 AM org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator initiateService
     [exec] WARN: HHH000342: Could not obtain connection to query metadata : The application must supply JDBC connections
     [exec] May 23, 2019 10:05:17 AM org.hibernate.dialect.Dialect <init>
     [exec] INFO: HHH000400: Using dialect: org.hibernate.dialect.H2Dialect
     [exec] May 23, 2019 10:05:18 AM org.hibernate.engine.transaction.jta.platform.internal.JtaPlatformInitiator initiateService
     [exec] INFO: HHH000490: Using JtaPlatform implementation: [org.hibernate.engine.transaction.jta.platform.internal.NoJtaPlatform]
     [exec] Finished booting Hibernate ORM session factory.
     [exec] 
     [exec] 
     [exec] ===== RESULT:
     [exec] Hibernate services loaded from Hibernate ORM module by bootstrapping a whole session factory: 
     [exec] [org.hibernate.cfg.beanvalidation.BeanValidationIntegrator@36916eb0, org.hibernate.secure.spi.JaccIntegrator@7bab3f1a, org.hibernate.cache.internal.CollectionCacheInvalidator@437da279]
     [exec] 
     [exec] 
     [exec] ======================================================
     [exec]                    ENDING EXECUTION                   
     [exec] ======================================================

I think the root cause of the problem may have something to do with how ORM uses an aggregated classloader.

Indeed, I've also experienced NoClassDefFoundError}}s in my modular application, and I had to declare dependencies from my application to other modules such as {{java.xml.bind, even though my application doesn't use those: only Hibernate ORM does. There is something fishy here...