This mini project shows the possible problem that Doctrine has with the XML driver when a 
foreign key is used as part of a composite primary key.

Setup:

1. Setup Doctrine pathes in $doctrineCommonPath, $doctrineDbalPath and $doctrineOrmPath (lines 7-9 index.php)
2. Choose which driver to use: Annotation or XML, configure in $driver (lines 48, 49 index.php)

The database is in database.sqlite, so there is no database setup to be done.

The problem will show up when you choose XML as driver and view index.php.
You will see that the database data isn't represented in the graph with the XML driver,
while it shows up perfectly with the Annotation driver.