I had written the PMD tool for Review Bot to configure the path to the

executable via the UI, but that approach is a little problematic in the case

where there are multiple workers running. In that case, a worker that didn't

have a valid PMD installation would take the task off the queue and then report

an error (even if there was a worker that could handle it).
I've added an optional config file for the worker, which can be used to

configure the path. If the path is unconfigured, or misconfigured, the worker

will not listen for PMD changes.
This config file will be used for more stuff in the future.

Ran the worker and saw that it loaded the config file correctly.