Jozef,

I made a confirmation for the issue as following:

After I removed all @Embeddable from the demo, the issue did not happen. And, after I recovered a @Embeddable from some classes (eg. the following liking),

@Embeddable
public class Delivery implements Serializable {
...
}

The issue still did not happen.

However, after I recovered a @Embeddable from RouteSpecification,

@Embeddable
public class RouteSpecification extends AbstractSpecification<Itinerary> implements Serializable {

@ManyToOne
...
}

The issue happened again.

Only difference is that RouteSpecification extends a base class with generic parameter.

Then, I removed all @Embeddable and only recovered Delivery class and started to make the following experiments:

1) I added an interface called "TestInf1" without generic parameter, and made Delivery class implements the interface
While deploying, the issue did not happen.

2) I added an base class called "TestInf1BaseClass" which implements the "TestInf1" interface, and made Delivery class extends the base class.

While deploying, the issue did not happen.

3) I made the "TestInf1" interface with generic parameter, and made Delivery class implements the interface with generic parameter
While deploying, the issue happen again.

4) I made the "TestInf1BaseClass" base class implements the "TestInf1" interface with generic parameter, and made Delivery class extends the "TestInf1BaseClass" with generic parameter (the case is the same as RouteSpecification class)

While deploying, the issue happen again.

So, based on the above results,

While combining @Embeddable with interface or base class with generic parameter, the issue will happen.

Thanks
--Tang