ConcurrentModificationException using roo and manytomany relationship

When using roo generated forms with manytomany relationships i get a ConcurrentModificationException when i try to remove a manytomany related entity. For example if i have a pizza with toppings and create a new pizza and add a topping everything works as expected. When i then try to update the pizza entity by removing the topping i get the exception.

My issue is described in Ticket #6933 which concerns customfield and is marked as fixed. I get the exception in the exact same point as described in the issue in MutableLocalEntityProvider.updateEntityProperty() when calling entityManager.flush.

Any ideas or workarounds are greatly appreciated.

Thank you.