The signal method of ServiceTaskDelegateExpressionActivityBehavior does not setup the multi instance behavior correctly when using a delegateExpression to a prototype scoped spring bean. This causes the "loop" to terminate when signalled.
The AbstractBpmnActivityBehavior.multiInstanceActivityBehavior reference is not assigned before the activity is triggered/signalled causing the activity to behave as a normal activity when executing the leave from with the signal.
A service task with multi instance properties setup.
A delegateExpression to a prototype scoped spring bean.
The bean is a subsclass of ReceiveTaskActivityBehavior and thus requires a signal to continue.