OK I think i figured it out - not sure though exactly the reason: It seems that i need to have a stream type - Generic Type of the super class - rather than a Pojo of the concrete generated class. It seems like the operation definition otherwise cannot load the Pojo class on the task creation. So - if i don't declare the map produced type as the concrete generated class and then work around the keyby which cannot use a field name to a key selector. Doing all of that seems to work. Will be happy to hear about the reason for it more in depth if anyone knows.
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