Consider the following build.xml script:

<?xml version="1.0" encoding="UTF-8"?>
<project name="testing" basedir=".">
  <target name="all">
    <script language="javascript">
      <![CDATA[
        project.setProperty("beans", "cheese");
      ]]>
    </script>
    <echo>Current beans=${beans}.</echo>
  </target>
</project>

Executing "ant all" results in the following error:

all:
   [script] Jan 09, 2015 1:10:25 PM org.apache.bsf.BSFManager loadScriptingEngine
   [script] SEVERE: Exception :
   [script] java.lang.NoClassDefFoundError: org/mozilla/javascript/EvaluatorException
   [script]     at java.lang.Class.getDeclaredConstructors0(Native Method)
   [script]     at java.lang.Class.privateGetDeclaredConstructors(Class.java:2663)
   [script]     at java.lang.Class.getConstructor0(Class.java:3067)
   [script]     at java.lang.Class.newInstance(Class.java:408)
   [script]     at org.apache.bsf.BSFManager.loadScriptingEngine(BSFManager.java:697)
   [script]     at org.apache.bsf.BSFManager.exec(BSFManager.java:485)
   [script]     at org.apache.tools.ant.util.optional.ScriptRunner.executeScript(ScriptRunner.java:100)
   [script]     at org.apache.tools.ant.taskdefs.optional.Script.execute(Script.java:52)
   [script]     at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:292)
   [script]     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   [script]     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
   [script]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
   [script]     at java.lang.reflect.Method.invoke(Method.java:483)
   [script]     at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
   [script]     at org.apache.tools.ant.Task.perform(Task.java:348)
   [script]     at org.apache.tools.ant.Target.execute(Target.java:435)
   [script]     at org.apache.tools.ant.Target.performTasks(Target.java:456)
   [script]     at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1393)
   [script]     at org.apache.tools.ant.Project.executeTarget(Project.java:1364)
   [script]     at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
   [script]     at org.apache.tools.ant.Project.executeTargets(Project.java:1248)
   [script]     at org.apache.tools.ant.Main.runBuild(Main.java:851)
   [script]     at org.apache.tools.ant.Main.startAnt(Main.java:235)
   [script]     at org.apache.tools.ant.launch.Launcher.run(Launcher.java:280)
   [script]     at org.apache.tools.ant.launch.Launcher.main(Launcher.java:109)
   [script] Caused by: java.lang.ClassNotFoundException: org.mozilla.javascript.EvaluatorException
   [script]     at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
   [script]     at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
   [script]     at java.security.AccessController.doPrivileged(Native Method)
   [script]     at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
   [script]     at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
   [script]     at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
   [script]     at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
   [script]     ... 25 more
   [script] 

BUILD FAILED

Adding "rhino" to the /etc/ant.d/apache-bsf config fixes this.