Amplify: 'id' column generated even after defining custom primary key column only

We are using Amplify to create a model. And using AppSync mutations and queries to store and access data from those Dynamo DB tables. We defined a custom primary key. Reference: type Movie @model @auth(rules: [{ allow: public}]) { imdb: ID! @primaryKey title: String! status: MovieStatus! rating: Int! description: String } All the generated files using amplify codegen and amplify codegen-models are correct without any 'id' column as input field. But when we run the mutation to create a record, we can see in the Dynamo DB table that a column 'id' is auto generated. Is there anything we are doing that or is that expected to be generated?