To quote my post Tuesday about Railo bug 147:
Railo has an issue with non-defaulted, non-required, numeric method arguments that are omitted from a call. I added it as bug 147 in JIRA.
Turns out I was a bit incorrect – I'd forgotten that method was proxied by ColdSpring's AOP engine (which is exactly what's supposed to happen with AOP), and that's where the bug actually resided. Railo was returning "[runtime expression]" as the default value for the argument within the function metadata, which ColdSpring was faithfully writing into the proxy method that it generates.
In any case, got a JIRA update from Michael to say it's been resolved, so the next build should have it fixed up.
I've been quite impressed with Railo in terms of fixing bugs. I sent a bug report in a year or so ago about imageCFC and they added it to the next build within a couple days.