I found the solution if anyone is curious…
I ended up leveraging spring injection to get the TaskService
in the war application configuration file
<bean id="getAttachmentClass" class="com.myco.activiti.poc.GetAttachmentClass">
<property name="taskService" ref="taskService"/>
</bean>
In the bpmn20 file I used an expresion for the service task….
#{getAttachmentClass.execute(execution)}