+----------+           +----------+
|  Animal  |<|---------|   Dog    |
+----------+           +----------+

+----------+           +----------+
|   Car    |<>---------|  Wheel   |
+----------+           +----------+

+----------+           +----------+
|  Order   |*----------| LineItem |
+----------+           +----------+

+----------+           +----------+
|  Cat     |---------|>|  Pet     |
+----------+           +----------+
