HHH-18693 Hibernate Processor does not handle inner types

[cigaly]

See Jira Issue HHH-18693

This is still work in progress, not to be merged with main branch, at least not immediately.

For each (static) inner non-private class one meta-model class will be generated.

Naming is as follows. If we have:

class A {
    ...
    @Entity
    static class B {
        ...
    }
    ...
}

Generated class will be named A_B_

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[cigaly]

Some existing test classes were changed to make inner classes non-private. Otherwise such class could not be referenced from meta model class.

[gavinking]

Thanks for working on this @cigaly !