Warnings Header
Use the Warning header to return warnings, such as
the use of a deprecated version of the API.
Header Field Name and Values
Field name: Warning
Field values:
- warningCode
- warningMessage
For warnings about deprecated API versions, the warningCode is 299.
Example: Warning: 299 - "This API is deprecated and will be removed by Summer '22. Please see https://help.salesforce.com/articleView?id=000351312 for details."