Why do I get the following NullPointerException when using tools?

 [wstools] java.lang.NullPointerException
  [wstools]     at java.lang.System.arraycopy(Native Method)
  [wstools]     at org.apache.xerces.impl.xs.XSModelImpl.getAnnotations(Unknown Source)
  [wstools]     at org.jboss.ws.metadata.wsdl.xmlschema.WSSchemaUtils.copyXSModel(WSSchemaUtils.java:737)
  [wstools]     at org.jboss.ws.tools.JavaToXSD.parseSchema(JavaToXSD.java:201)
  [wstools]     at org.jboss.ws.metadata.wsdl.WSDL11Reader.processTypes(WSDL11Reader.java:227)
  [wstools]     at org.jboss.ws.metadata.wsdl.WSDL11Reader.processDefinition(WSDL11Reader.java:118)
  [wstools]     at org.jboss.ws.metadata.wsdl.WSDLDefinitionsFactory.parse(WSDLDefinitionsFactory.java:145)
  [wstools]     at org.jboss.ws.tools.WSDLToJava.convertWSDL2Java(WSDLToJava.java:121)
  [wstools]     at org.jboss.ws.tools.helpers.ToolsHelper.handleWSDLToJavaGeneration(ToolsHelper.java:323)
  [wstools]     at org.jboss.ws.tools.WSTools.process(WSTools.java:138)
  [wstools]     at org.jboss.ws.tools.WSTools.generate(WSTools.java:120)
  [wstools]     at org.jboss.ws.tools.ant.wstools.execute(wstools.java:103)
   ...

This is a xerces bug that was fixed in 2.7.0. Unfortunately, the latest version of ant comes with 2.6.2. You need to update the xerces jars in your ANT_HOME/lib directory to be at least 2.7.0.