There was some new code recently added passing around an extra parameter that did nothing more than stick an extra string in the logging. The reasoning is

...it is pretty much impossible to trace the flow of a single request to the server when other requests are coming in. I propose we add a simple prefix to each log [...] that will contain a unique ID per request that can be grepped in the logs...

But it's actually not impossible to follow a single request, since each log entry includes the name of the thread. But if it helps him, it's fine with me as long as I don't have to maintain that code.

It's like that other almost as silly request from someone who has since left to rename certain threads because he wanted them to have certain names in the logs. Personally, I prefer keeping the thread names from the JVM or from the servlet engine, because they will be unique. I had to rework that thread renaming code after adding some other feature caused thread name collisions.