I have an optional include that references a resource on the classpath. In my production builds I don't include that resource at all. However, Logback is printing the following message:

16:22:35,720 |-ERROR in ch.qos.logback.core.joran.action.IncludeAction - Could not find resource corresponding to [logback-dev.xml]

Looking at IncludeAction it looks like there should be a if(!optional) around the code in the catch portion of the resourceAsURL.

I'll see if I can't get a pull request out there soon.

java version "1.7.0_19"
OpenJDK Runtime Environment (fedora-2.3.9.1.fc18-x86_64)
OpenJDK 64-Bit Server VM (build 23.7-b01, mixed mode)