Kodo / openjpa data cache watermark settings?

Question

I'm trying to find information on what triggers a data cache cleardown in kodo / openjpa.

I'm guessing there is a high watermark - at which point the cache will clear down data. Does it just remove a single item once you hit your cache size limit, or a whole load of stuff? Or maybe there is no clear down, and you simply get an error when attempting to cache an additional object when it's already full?

Sadly; The docs on oracle/apache websites dont make any reference to anything like this.

Thanks, Dan