Consider the validator expression {"a.b": {"$nin": [1, [2, 3, 4]]}} and the document {"a": [{"b": [1, 2]}, {"b": [3, 4]}]. This document will fail validation because the value '1' is present within {"b": [1, 2]}, but the generated error will report 'consideredValues: [1, 2, [1,2], 3, 4, [3,4]]' without specifying which of the considered values was found to be matching. Consider adding support for exposing matching values in the case of negation expressions like $nin where, because the operator has multiple arguments, it's not immediately obvious which of the values matched.