How to remove with Regex In Java

I have a sample data in the form of a string

[
  {
    "description": "Üntuk testing",
    "is_multiple_apply": true,
    "invoice": "invoice-Test",
    "fc_code": "invoice-fc-test",
    "promo_min_purchase_amount": 300,
    "promo_min_purchase_qty": 3,
    "promo_max_qty_applied": 2,
    "promo_date_end": "2020-08-15T23:59:00+0000",
    "promo_date_start": "2020-08-01T00:00:00+0000",
    "product_promo": [
      "{"plu":100,"qty":100,"discount":100,"discount_type":"AMOUNT"}"
    ]
  }
]

then in the product_promo object exactly here
> "{"plu":100,"qty":100,"discount":100,"discount_type":"AMOUNT"}"

• there is a quote outside the curly braces and I want to get rid of it

This is a working method for converting previous string data into available model ProductsPromoModel

public List<ProductsPromoModel> getProductsPromo() throws JsonMappingException, JsonProcessingException{
	    ObjectMapper mapper = new ObjectMapper();
	    List<ProductsPromoModel> productPromoMods = new ArrayList<>();
	    
	    productPromoMods = mapper.readValue(this.productsPromo.toString(), new TypeReference<List<ProductsPromoModel>>(){});
	      
	    return productPromoMods;
  }

but because there are quotes outside the curly braces. so the process occurs error

how to do it with regex?

You can do this with regex lookaheads and lookbehinds as follows:

yourString.replaceAll("\"(?=\\{)|(?<=\\})\"", "");

Or you can do two replacements that are a little less complicated:

yourString.replaceAll("\"\\{", "{").replaceAll("\\}\"", "}")