This method allows you to prevent the output ached from adding a vary:* header to the outgoing response when the cached response varies by parameter. This is useful for clients varying caching by query string because most clients will automatically vary by query string without requiring the vary:* header.
The use of the vary:* header can disable all client caching.
This is a convenience method to affect the VaryByHeaders property. Passing true to the method directs the HttpCachePolicy to ignore the * value for the VaryByHeaders property.