HttpAsyncExpectationVerifier defines a strategy to verify whether
or not an incoming HTTP request meets the target server's expectations.
A server that does not understand or is unable to comply with any of
the expectation values in the Expect field of a request MUST respond
with appropriate error status. The server MUST respond with a 417
(Expectation Failed) status if any of the expectations cannot be met
or, if there are other problems with the request, some other 4xx