reuse toJSON instances

E.g. I have type

data PaymentOptionsCommon id =
  PaymentOptions
    { poId          :: id
    , poPaymentType :: Maybe PaymentMethod
    , poPaymentNet  :: Maybe Int
    , poInstallment :: Maybe Int  -- days
    } deriving (Generic, Eq, Ord, Show)

type PaymentOptions   = PaymentOptionsCommon ()

And ToJSON instance like this:

instance FromJSON PaymentOptions where
  parseJSON = withObject "paymentOptions" $ \o -> do
    poId          <- skip
    poPaymentType <- o .:? "type"
    poPaymentNet  <- o .:? "deffered"
    poInstallment <- o .:? "installment"
    return $! PaymentOptions{..}

instance ToJSON PaymentOptions where
  toJSON PaymentOptions{..} =
    object
      [ "type"        .= poPaymentType
      , "deffered"    .= poPaymentNet
      , "installment" .= poInstallment
      ]

And auto-generated ToSchema instance:

instance ToSchema PaymentOptions

So, swagger would looks like:

  PaymentOptionsCommon:
    required:
      - poId
    properties:
      poId:
        items: []
        type: array
      poPaymentType:
        $ref: '#/definitions/PaymentMethod'
      poPaymentNet:
        maximum: 9223372036854776000
        minimum: -9223372036854776000
        type: integer
      poInstallment:
        maximum: 9223372036854776000
        minimum: -9223372036854776000
        type: integer
    type: object

But instead I expect to see something more like:

  PaymentOptions:
    properties:
      type:
        $ref: '#/definitions/PaymentMethod'
      deffered:
        maximum: 9223372036854776000
        minimum: -9223372036854776000
        type: integer
      installment:
        maximum: 9223372036854776000
        minimum: -9223372036854776000
        type: integer
    type: object

Without prefixes

The question is: how to do this?