[{hasIdentifier:[{"identifier":{"type":"xxxx","value":"1111"},"origin":"example.com","score":8.0},{"identifier":{"type":"yyyyy","value":"222"},"origin":"example.com","score":8.0},{"identifier":{"type":"zzzzz","value":"3333"},"origin":"https://olkdghf.com","score":8.0}]}]

db.collection.update({},[{$set:{hasIdentifier:{$map:{input:"$hasIdentifier",in:{$mergeObjects:["$$this",{"identifier":{$mergeObjects:["$$this.identifier",{type:["$$this.identifier.type"]}]}}]}}}}}])