Try this one.. I was able to get it to build

createJar:
    [javac] /Users/Nicholas/Sites/Railo-MongoDB-Cache-Extension/Railo-MongoDB-Cache-Extension/build.xml:66: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=last; set to false for repeatable builds
    [javac] Compiling 7 source files to /Users/Nicholas/Sites/Railo-MongoDB-Cache-Extension/Railo-MongoDB-Cache-Extension/extension/bin
    [javac] Note: Some input files use or override a deprecated API.
    [javac] Note: Recompile with -Xlint:deprecation for details.
    [javac] Note: Some input files use unchecked or unsafe operations.
    [javac] Note: Recompile with -Xlint:unchecked for details.
      [jar] Building jar: /Users/Nicholas/Sites/Railo-MongoDB-Cache-Extension/Railo-MongoDB-Cache-Extension/extension/lib/mongodb-cache.jar

BUILD SUCCESSFUL
Total time: 2 seconds