Add fields to shopping tab of an extension in configuration

To add fields in the shopping tab of an extension in website configuration,Edit the configuration folder of the corresponding extension. Add fields in the property of configuration.sample code is given below.

{
    "type": "object"
,	"subtab": {
    "id": "CUstomProducts"
,	"title": "Custom Products"
,	"docRef": ""
,	"description": "Custom Products form configuration"
,   "group": "shoppingApplication"
}
,	"properties": {
    "CUstomProducts.recipient": {
        "group": "shoppingApplication"
    ,   "subtab": "CustomProducts"
    ,   "type": "string"
    ,	"title": "Recipient email"
    ,	"description": "Enter the email please"
    }
,	"CUstomProducts.subject": {
        "group": "shoppingApplication"
    ,   "subtab": "CustomProducts"
    ,	"type": "string"
    ,	"title": "Email's subject"
    ,	"description": "Type the email's subject"
    ,	"default": "New contact from website"
    }
,	"CUstomProducts.sender": {
        "group": "shoppingApplication"
    ,   "subtab": "CustomProducts"
    ,	"type": "integer"
    ,	"title": "Sender ID"
    ,	"description": "Provide the ID for the sender"
    }
}
}