REST API ERROR: "INVALID_VALUE" - "There is no field named Account.UnappliedCreditMemoAmount."

[Rossi]

When using the following query (POST at https://rest.apisandbox.zuora.com/v1/object/export), I'm getting the error below saying "There is no field named Account.UnappliedCreditMemoAmount.", however, I have Credit Memo feature enabled in my tenant. 

{
"Format": "csv",
"Query": "SELECT Account.UnappliedCreditMemoAmount FROM Invoice"
}

  "Errors": [
  {
    "Code": "INVALID_VALUE",
    "Message": "There is no field named Account.UnappliedCreditMemoAmount."
  }
],
"Success": false
}

[Rossi · Accepted solution]

Solution:

The field UnappliedCreditMemoAmount of Account was introduced on Zuora API version 82. To override, you will need to add the following to your HTTP header

x-zuora-wsdl-version: 82.0

Optionally you can replace 83.0 with your preferred WSDL as required, or as appropriate for your missing field

NOTE: 
This override should only be used within /v1/action/ APIs documented in our developer center linked above.  Using in other REST calls may have an unknown consequence to otherwise functional API.