PreFlightExtraction
Determines which parts of the request should be pre-extracted to check for presence before being passed to the ultimate HttpHandler for this route. Choice will be determined by two competing scenarios:
By selecting a All of the request to be pre-extracted (the default), we can collect all errors at once to be returned to the client - which is more user friendly. If we fall back on just the Lens usage in the HttpHandler code, only the first failing Lens extraction will be reported.
Not pre-checking parts of the request is more efficient, which may be important given parsing of request bodies could be expensive and pre-flight-extraction would involve performing this operation twice.