id property
Identity of the server.
This is used as a prefix to the request number to form the Request.id to identify the Request. This is commonly used in log messages:
myLog.info("[${req.id}] something happened");
The default value of the empty string is usually fine for most applications, since most applications are only running one Server. But if multiple servers are running, give them each a unique id so the requests can be uniquely identified.
Implementation
String id = '';