New takes an eventPoller and eventFlusher and returns a Server.

ShutdownReasonFieldExtensionType is the field name for shutdown reason in shutdown reason event.

ShutdownReasonFieldInvokedFunctionARN is the field name used for function arn in shutdown reason event.

ShutdownReasonFieldRequestID is the field name used for request ID in shutdown reason event.

Server represents a server that polls and processes Lambda extension events.