what is the best way to organize root resolvers?

[videni]

I try to create two root resolvers in different file.

create_customer.rs

#[graphql_object(context = Context)]
impl Mutation {
    async fn create_customer(
        context: &Context,
        customer: CustomerCreateInput,
    ) -> FieldResult<CreateCustomerResult> {
}
}

If I don't put another graphql_object attribute, then rust will complain generate_customer_token not used.
generate_customer_token.rs

#[graphql_object(context = Context)]
impl Mutation {
    async fn generate_customer_token(
        context: &Context,
        username: String,
        password: String,
    ) -> FieldResult<CustomerToken> {
}

I got

{
	"resource": "/Users/acme/www/test/src/resolver/create_customer.rs",
	"owner": "rustc",
	"code": {
		"value": "E0119",
		"target": {
			"$mid": 1,
			"external": "https://doc.rust-lang.org/error-index.html#E0119",
			"path": "/error-index.html",
			"scheme": "https",
			"authority": "doc.rust-lang.org",
			"fragment": "E0119"
		}
	},
	"severity": 8,
	"message": "conflicting implementations of trait `juniper::GraphQLValueAsync<_>` for type `graphql::Mutation`\nconflicting implementation for `graphql::Mutation`",
	"source": "rustc",
	"startLineNumber": 46,
	"startColumn": 1,
	"endLineNumber": 46,
	"endColumn": 37,
	"relatedInformation": [
		{
			"startLineNumber": 18,
			"startColumn": 1,
			"endLineNumber": 18,
			"endColumn": 37,
			"message": "first implementation here",
			"resource": "/Users/acme/www/test/src/resolver/generate_customer_token.rs"
		}
	]
}

I am very curious, is your project really that simple you can put all your root resolvers in a single file?