Create an attachment

{
  "data": {
    "attributes": {
      "name": "DDT transport document",
      "description": "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.",
      "url": "https://s3.yourdomain.com/attachment.pdf",
      "reference": "ANY-EXTERNAL-REFEFERNCE",
      "reference_origin": "ANY-EXTERNAL-REFEFERNCE-ORIGIN",
      "metadata": {
        "foo": "bar"
      }
    },
    "relationships": {
      "attachable": {
        "data": {
          "id": "XAyRWNUzyN",
          "attributes": {
            "number": 1234,
            "name": "EU Market",
            "code": "europe1",
            "facebook_pixel_id": "1234567890",
            "checkout_url": "https://checkout.yourbrand.com/:order_id",
            "external_prices_url": "https://external_prices.yourbrand.com",
            "external_order_validation_url": "https://external_validation.yourbrand.com",
            "private": true,
            "shipping_cost_cutoff": 3,
            "disabled_at": "2018-01-01T12:00:00.000Z",
            "shared_secret": "1c0994cc4e996e8c6ee56a2198f66f3c",
            "external_includes": [
              "order.line_item_options"
            ],
            "created_at": "2018-01-01T12:00:00.000Z",
            "updated_at": "2018-01-01T12:00:00.000Z",
            "reference": "ANY-EXTERNAL-REFEFERNCE",
            "reference_origin": "ANY-EXTERNAL-REFEFERNCE-ORIGIN",
            "metadata": {
              "foo": "bar"
            }
          },
          "relationships": {
            "merchant": {
              "data": {
                "id": "XAyRWNUzyN"
              }
            },
            "price_list": {
              "data": {
                "id": "XAyRWNUzyN"
              }
            },
            "base_price_list": {
              "data": {
                "id": "XAyRWNUzyN"
              }
            },
            "inventory_model": {
              "data": {
                "id": "XAyRWNUzyN"
              }
            },
            "subscription_model": {
              "data": {
                "id": "XAyRWNUzyN"
              }
            },
            "discount_engine": {
              "data": {
                "id": "XAyRWNUzyN"
              }
            },
            "tax_calculator": {
              "data": {
                "id": "XAyRWNUzyN",
                "attributes": {
                  "name": "Personal tax calculator",
                  "type": "avalara_accounts",
                  "created_at": "2018-01-01T12:00:00.000Z",
                  "updated_at": "2018-01-01T12:00:00.000Z",
                  "reference": "ANY-EXTERNAL-REFEFERNCE",
                  "reference_origin": "ANY-EXTERNAL-REFEFERNCE-ORIGIN",
                  "metadata": {
                    "foo": "bar"
                  },
                  "username": "user@mydomain.com",
                  "company_code": "MYCOMPANY",
                  "commit_invoice": true,
                  "ddp": true,
                  "pass_tax_exemption_code": true
                },
                "relationships": {
                  "markets": {
                    "data": {
                      "id": "XAyRWNUzyN"
                    }
                  },
                  "attachments": {
                    "data": {
                      "id": "XAyRWNUzyN"
                    }
                  },
                  "events": {
                    "data": {
                      "id": "XAyRWNUzyN"
                    }
                  },
                  "event_stores": {
                    "data": {
                      "id": "XAyRWNUzyN"
                    }
                  },
                  "tax_categories": {
                    "data": {
                      "id": "XAyRWNUzyN"
                    }
                  }
                }
              }
            },
            "customer_group": {
              "data": {
                "id": "XAyRWNUzyN"
              }
            },
            "geocoder": {
              "data": {
                "id": "XAyRWNUzyN"
              }
            },
            "default_shipping_method": {
              "data": {
                "id": "XAyRWNUzyN"
              }
            },
            "default_payment_method": {
              "data": {
                "id": "XAyRWNUzyN"
              }
            },
            "stores": {
              "data": {
                "id": "XAyRWNUzyN"
              }
            },
            "price_list_schedulers": {
              "data": {
                "id": "XAyRWNUzyN"
              }
            },
            "order_validation_rules": {
              "data": {
                "id": "XAyRWNUzyN"
              }
            },
            "attachments": {
              "data": {
                "id": "XAyRWNUzyN"
              }
            },
            "event_stores": {
              "data": {
                "id": "XAyRWNUzyN"
              }
            }
          }
        }
      }
    }
  }
}