Message Title

using hibernate-jpamodelgen-4.3.6.Final,
if you go inside org.hibernate.jpamodelgen.JPAMetaModelEntityProcessor#process method you'll see the following code:

        Set<? extends Element> elements = roundEnvironment.getRootElements();
        for ( Element element : elements ) {
            if ( isJPAEntity( element ) ) {
                context.logMessage( Diagnostic.Kind.OTHER, "Processing annotated class " + element.toString() );
                handleRootElementAnnotationMirrors( element );
            }
        }

        Set<? extends Element> elements = roundEnvironment.getRootElements();
        for ( Element element : elements ) {
            if ( isJPAEntity( element ) ) {
                // HHH-8714 begins
                for (Element enclosedElement : element.getEnclosedElements()) {
                    if ( isJPAEntity(enclosedElement)) {
                        context.logMessage( Diagnostic.Kind.OTHER, "Processing inner annotated class " + element.toString() );
                        handleRootElementAnnotationMirrors( enclosedElement );
                    }
                }
                // HHH-8714 ends
                context.logMessage( Diagnostic.Kind.OTHER, "Processing annotated class " + element.toString() );
                handleRootElementAnnotationMirrors( element );
            }
        }

I've just ran the patched code and it appears that the composite id class is getting generated in it's proper (non-inner) class.
Note: I do not think we need to recurse within all the enclosed element ; to me, it would appear a bit weird to stack multiple inner class.