Interface to allow consumers to attach themselves to a channel’s
notification callbacks/loadgroup and determine if a given channel
request should be intercepted before any network request is initiated.
Returns true if a channel should avoid initiating any network
requests until specifically instructed to do so.
| aURI | the URI being requested by a channel |
Notification when a given intercepted channel is prepared to accept a synthesized
response via the provided stream.
| aChannel | the controlling interface for a channel that has been intercepted |
| aStream | a stream directly into the channel's synthesized response body |