Adding dependencies to packages which install versioned JARs is tricky business. It involves requiring a specific version of the package, which isn't a good idea for packages which aren't slotted.
Created attachment 59341 [details, diff] patch against servletapi-2.3-r1.ebuild to no longer use versioned JAR This patch now installs servlet.jar, instead of servletapi-2.3.jar. I choose this name because of the JAR that the ant creates.
fixed in cvs, also updated references.