尝试使用graphql发送输入对象时，该对象的属性之一接收到空值

I'm using go on the server side with graphql, and angular6 with apollo on client side.

I'm trying to send the following object in mutation:

{
  "deliveryId": 1,
  "products": [{
    "id": 3,
    "quantity": 1
  }],
  "payment": {
    "name": "kfir ozer",
    "number": "4580 0307 6696 9445",
    "expiry": "02 / 122",
    "cvc": "332"
  }
}

I paste this object to the following function to send it to the server:

addOrderInfo(order) {
  return this.apollo.mutate({
    mutation: gql `
      mutation AddOrderInfo($order: Order!) {
        addOrderInfo(order: $order) {
          id
        }
      }
    `,
    variables: {
      order
    }
  });
}

and now the server side..

this is how I configure the relevant types:

cartProduct: = graphql.NewInputObject(
  graphql.InputObjectConfig {
    Name: "CartProduct",
    Fields: graphql.InputObjectConfigFieldMap {
      "id": & graphql.InputObjectFieldConfig {
        Type: graphql.Int,
      },
      "quantity": & graphql.InputObjectFieldConfig {
        Type: graphql.Int,
      },
    },
  },
)
payment: = graphql.NewInputObject(
  graphql.InputObjectConfig {
    Name: "CreditCardPayment",
    Fields: graphql.InputObjectConfigFieldMap {
      "name": & graphql.InputObjectFieldConfig {
        Type: graphql.String,
      },
      "number": & graphql.InputObjectFieldConfig {
        Type: graphql.String,
      },
      "expiry": & graphql.InputObjectFieldConfig {
        Type: graphql.String,
      },
      "cvc": & graphql.InputObjectFieldConfig {
        Type: graphql.String,
      },
    },
  },
)
order: = graphql.NewInputObject(
  graphql.InputObjectConfig {
    Name: "Order",
    Fields: graphql.InputObjectConfigFieldMap {
      "deliveryId": & graphql.InputObjectFieldConfig {
        Type: graphql.Int,
      },
      "payment": & graphql.InputObjectFieldConfig {
        Type: payment,
      },
      "products": & graphql.InputObjectFieldConfig {
        Type: graphql.NewList(cartProduct),
      },
    },
  },
)

and this is how I set the mutation:

RootMutation: = graphql.NewObject(graphql.ObjectConfig {
  Name: "Mutation",
  Fields: graphql.Fields {
      "addOrderInfo": & graphql.Field {
        Type: ContactUsType,
        Args: graphql.FieldConfigArgument {
          "order": & graphql.ArgumentConfig {
            Type: order,
          },
        },
        Resolve: func(params graphql.ResolveParams)(interface {}, error) {
          ### here I created a breakpoint with intellij
          ### and noticed that the payment related values
          ### are empty strings
        },
      },
    }
    ...
  }
}

and on the server side... the params returns the proper data but the payment property contains the expiry, cvc, name and number properties but they are an empty string instead of the actual values.

what am I missing?

thanks