Axis2 distro does not package Xerces with the commandline tools

The following exception occurs with bpelc on Mac OS X:

$ bpelc HelloWorld2.bpel
java org.apache.ode.tools.bpelc.cline.BpelC: org/apache/xerces/jaxp/DocumentBuilderFactoryImpl
java.lang.NoClassDefFoundError: org/apache/xerces/jaxp/DocumentBuilderFactoryImpl
at org.apache.ode.bpel.compiler.bom.BpelObjectFactory.parse(BpelObjectFactory.java:287)
at org.apache.ode.bpel.compiler.BpelC.compile(BpelC.java:324)
at org.apache.ode.tools.bpelc.BpelCompileCommand.execute(BpelCompileCommand.java:122)
at org.apache.ode.tools.bpelc.cline.BpelC.main(BpelC.java:99)

$ java -version
java version "1.5.0_07"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_07-164)
Java HotSpot(TM) Client VM (build 1.5.0_07-87, mixed mode, sharing)

Adding Xerces to the lib directory of the distribution resolves the issue. The issue may be masked by the inclusion of Xerces in other JVMs.