HHH-18982 make BeanContainer loadable as a Java service

[gavinking]

also remove unnecessary use of reflection for creation of the CDI BeanContainer

[Please describe here what your change is about]

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https://hibernate.atlassian.net/browse/HHH-18982

[gavinking]

@sebersole in my testing, the use of reflection in CdiBeanContainerBuilder appears to not be needed.

[sebersole]

@sebersole in my testing, the use of reflection in CdiBeanContainerBuilder appears to not be needed.

The pertinent javadoc is :

 * We need to avoid statically linking CDI classed into the ClassLoader which
 * would lead to errors if CDI is not available on the classpath.

If CDI is not in the classpath and it stil works, then I'm confused but great

[gavinking]

Well I mean if the classes that import CDI types are never loaded, then CDI types aren't loaded either.

[gavinking]

The VM won't load classes it doesn't need.

[sebersole]

Depends if CDI is always on the classpath of the user code when run in a container. Wild Fly, e.g., always passes Hibernate a BeanManager reference iiuc which would trigger this code.

[gavinking]

But if WildFly passes a BeanManager then we're going to instantiate a CdiBeanContainerXxxxAccess and those classes are going to be loaded anyway, no?

[sebersole]

Sure. But the reflection was intended to give a useful waring -

[subsystem]  WARN org.hibernate.orm.beans ManagedBeanRegistryInitiator:67 - HHH10005001: An explicit CDI BeanManager reference [java.lang.Object@16132f21] was passed to Hibernate, but CDI is not available on the Hibernate ClassLoader. This is likely going to lead to exceptions later on in bootstrap.

Ultimately the exception will be the same ofc -

Unable to create requested service [org.hibernate.resource.beans.spi.ManagedBeanRegistry] due to: Unable to load class [jakarta.enterprise.inject.spi.BeanManager]
org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.resource.beans.spi.ManagedBeanRegistry] due to: Unable to load class [jakarta.enterprise.inject.spi.BeanManager]
...

Now, we could look at simply catching the class-loading exception somewhere and logging the nice warning.

[gavinking]

Now, we could look at simply catching the class-loading exception somewhere and logging the nice warning

OK, so what I did instead was do the check upfront and throw a sensible exception.

If this change breaks anything we will know soon enough, and the cause of breakage will be clear.