How do I generate exportable graphql input types using `amplify codegen`?

** Which Category is your question related to? **

codegen

** What AWS Services are you utilizing? **

appsync, dynamodb

** Provide additional details e.g. code snippets **

I'm trying to follow the documentation here https://aws-amplify.github.io/docs/js/api#aws-appsync-sdk and there is an example for using `buildMutation` given:

```
import { listTodos } from './graphql/queries';
import { createTodo, CreateTodoInput } from './graphql/mutations';

(async () => {
const result = await client.mutate(buildMutation(client,
gql(createTodo),
{
inputType: gql(CreateTodoInput),
variables: {
input: {
name: 'Use AppSync',
description: 'Realtime and Offline',
}
}
},
(_variables) => [ gql(listTodos) ],
'Todo'));

console.log(result);
})();
```

Specifically, `import { createTodo, CreateTodoInput } from './graphql/mutations';`

When I run `amplify codegen`, the generated `src/graphql/mutations.js` does *not* include `input` types (e.g. CreateTodoInput in the case of the example given). How do I generate these, so I can use `buildMutation` in a similar manner?

Just noticed I used `aws` instead of `amplify` everywhere. My bad :) `aws` mindshare is strong

Start with the documented buildMutation example at the AWS Amplify API link and compare it with the generated src/graphql/mutations.js produced by amplify codegen. Check whether the codegen entry point supports exporting input types such as CreateTodoInput, then clarify the supported workflow or update the documentation so the example matches generated output.

Written by the indexing model from the issue text.