This is a simple test that demonstrates how Hibernate's JPA Metamodel Generator puts its source files in the wrong place if you're using AspectJ as a compiler.
The case associated with this in the Hibernate bug tracker is at: https://hibernate.atlassian.net/browse/HHH-10626
To demonstrate the problem, simply run:
mvn compile
One would expect the generated sources to be under target/generated-sources/,
but they are actually placed in the top-level project directory.