mongoTemplate sends strings as objectIds

mongoTemplate seems to automatically convert strings to ObjectIds, which can lead to undesired behavior

I'm using mongo 6.x and spring-data-mongo 4.0.8

See the following test and its log output:

    @Test
    void mongoObjectIdConversion() {
        ObjectId objectId = ObjectId.get();
        mongoTemplate.updateFirst(Query.query(where("_id").is(objectId)), new Update().set("foo", "bar"), "testcol");
        mongoTemplate.updateFirst(Query.query(where("_id").is(objectId.toHexString())), new Update().set("foo", "bar"), "testcol");
        mongoTemplate.updateFirst(Query.query(where("_id").is(objectId.toHexString() + "x")), new Update().set("foo", "bar"), "testcol");
    }

2023-08-07T14:15:12.282+02:00 DEBUG 15565 --- [           main] o.s.data.mongodb.core.MongoTemplate      : Calling update using query: { "_id" : { "$oid" : "64d0e050450ebf73e850fafc"}} and update: { "$set" : { "foo" : "bar"}} in collection: testcol
2023-08-07T14:15:12.287+02:00 DEBUG 15565 --- [           main] o.s.data.mongodb.core.MongoTemplate      : Calling update using query: { "_id" : { "$oid" : "64d0e050450ebf73e850fafc"}} and update: { "$set" : { "foo" : "bar"}} in collection: testcol
2023-08-07T14:15:12.289+02:00 DEBUG 15565 --- [           main] o.s.data.mongodb.core.MongoTemplate      : Calling update using query: { "_id" : "64d0e050450ebf73e850fafcx"} and update: { "$set" : { "foo" : "bar"}} in collection: testcol

When the records are effectively using "String" as datatype for _id, then the second query will not update the records. I would expect the update to keep the original data type.

Start by reproducing the supplied mongoObjectIdConversion test with MongoDB 6.x and spring-data-mongo 4.0.8, then trace MongoTemplate's query conversion for _id values. Compare the logged queries for ObjectId, a valid hexadecimal string, and a non-hexadecimal string. Done means a String _id remains a String rather than being converted to an ObjectId.