[{"accountCreation":[{"startDateTime":"","endDateTime":"","isDone":"Yes","test":true}]}]

db.collection.update({},[{"$project":{accountCreation:{"$map":{"input":"$accountCreation","as":"ac","in":{"$objectToArray":"$$ac"}}}}},{"$project":{accountCreation:{"$map":{"input":"$accountCreation","as":"ac","in":{"$map":{"input":"$$ac","as":"kv","in":{"$cond":{"if":{$eq:["$$kv.k","isDone"]},"then":{"k":"done","v":"$$kv.v"},"else":"$$kv"}}}}}}}},{"$project":{accountCreation:{"$map":{"input":"$accountCreation","as":"ac","in":{"$arrayToObject":"$$ac"}}}}}])