Filters

Filter objects intercept requests and responses during processing, and change them as follows:

Leave the request, response, and contexts unchanged. For example, the filter can simply can log the context as it passes through the filter.
In the request flow, change any aspect of the request (such as the URL, headers, or entity), or replace the request with a new Request object.
In the response flow, change any aspect of the response (such as the status, headers, or entity), or return a new Response instance

IG provides the following filters: