Function entity_element_scopes 

pub fn entity_element_scopes(
    engine: &MappingEngine,
    json: &Value,
    tree: &AssembledTree,
) -> HashMap<ElementKey, InstancePath>

The group instance each entity element of json becomes in tree (the reverse mapping of json by engine).

Found by removal: the element is taken out of the JSON, the rest reverse- mapped again, and the repetition that is no longer there is the element’s. Only an element whose removal takes away exactly one repetition (with the groups nested in it) gets an entry. One that spans several — or none, when it only contributes fields to a repetition other elements also fill — gets none, and its conditions are evaluated message-wide, as without a scope.