When an EXISTS-over-UNNEST subquery body references a field from the outer entity (e.g. WHERE EXISTS (FROM c.lineItems li WHERE li.qty > c.minQty)), the current translator throws FeatureNotSupportedException because $elemMatch cannot reference outer document fields directly.

Supporting this shape requires translating to $expr with $anyElementTrue+$map, a structurally different MQL form from the simple $elemMatch used for non-correlated EXISTS-over-UNNEST.