Swagger-codegen has made a new property on his own!

[makarac]

I had a problem with the symbol codes '$' and '@' in my Open API 3.0 spec. The ISO 20021 standard has an object, called ActiveCurrencyAndAmount as below:

ActiveCurrencyAndAmount:
  required:
  - "$"
  - "@Ccy"
  type: object
  properties:
    "$":
      type: number
      format: float
      example: 839.6
    "@Ccy":
      pattern: '[A-Z]{3,3}'
      type: string
      example: ERU

---

the generated code for spring language produces the below code:
{
"Amt": {
"$": 839.6,
"@ccy": "string",
"atCcy": "USD"
},
it adds "atCcy" on his own, and it seems it made a new property.
Any one has encountered such issue? Is there any workaround on this?