I'm trying to add additional data to the `checkmo` payment method. I then need this additional data appear at the order Endpoint.

I plan on using this as a way of passing over a **sort code** / **account number** for direct debit payments. 

I have a system set up that places orders for Magento 2 with the API. A user enters name / address etc and this is sent over using the API. 

For payment method I need to pass over **sort code** / **account number**. Rather than creating a custom payment method for this, I would like to try and shoehorn this information into an existing one that won't be used on the actual Magento 2 site. 

The issue seems to be actually adding data into this, 

The [Swagger documentation](http://devdocs.magento.com/swagger/index.html) seems to have - 

```
payment": {
"account_status": "string",
"additional_data": "string",
"additional_information": [
  "string"
],

```

I have tried using this - 

```
{
"paymentMethod": {
"method": "checkmo",
"additional_data": {
"sortcode" :"00-00-00",
"account_number" : "12345678"
   }
 }
}

```

But this still comes out at the Endpoint as - 

```
"payment": {
    "account_status": null,
    "additional_information": [
        "Check / Money order",
        null,
        null
    ],

```

If I try to use `additonal information` instead - 

```
{
"paymentMethod": {
"method": "checkmo",
"additional_information": {
"sortcode" :"00-00-00",
"account_number" : "12345678"
 }
}

```

I get the error 

`Message: Property "AdditionalInformation" does not have corresponding setter in class "Magento\Quote\Api\Data\PaymentInterface".` 

Is there anyway to add this to an order preferably using checkmo payment method, and then have it appear at the endpoint?