I guess user can only set it via unique-id property, right? If so, it’s confusing because unique-id is unsigned. Not a big deal, though, we don’t have that many elements in a pipeline to overflow the integer, anyway.
unique-id : Unique ID for the element. Can be used to identify output of the element
flags: readable, writable, changeable only in NULL or READY state
Unsigned Integer. Range: 0 - 4294967295 Default: 15