The HTTP Service will use the return value of the createRequest callback as the request body (if supported by the
HTTP method). If this is an array of non-null HTTPRequestPart objects, then a multi-part request will
be formed. Otherwise the object is converted to a String and used.
This only caches status codes 2xx with a content length and size of less than 50k that are not immediately
written to file. The URL and the user name are used as cache keys. The total size of cacheable content and the
number of cached items is limited and automatically managed by the system.
Cache control information sent by the remote server is ignored.
Caching HTTP responses should be done very carefully. It is important to ensure that the response really depends
only on the URL and doesn't contain any remote state information or time information which is independent of the
URL. It is also important to verify that the application sends exactly the same URL multiple times.
The time to live for the cached content in seconds. A value of 0 or less disables caching.