JAXP SAXParserFactory has the setXIncludeAware method that reads like this:

> > public void setXIncludeAware(final boolean state) {
> > throw new UnsupportedOperationException(
> > "This parser does not support specification \""
> > + this.getClass().getPackage().getSpecificationTitle()
> > + "\" version \""
> > + this.getClass().getPackage().getSpecificationVersion()
> > + "\""
> > );
> > }

This most typically just results in the following error, which is not
useful at all:

> > Caused by: java.lang.UnsupportedOperationException: This parser does not support specification "null" version "null"
> > at javax.xml.parsers.SAXParserFactory.setXIncludeAware(SAXParserFactory.java:448)
> > at org.jclouds.http.functions.config.ParserModule.provideSAXParserFactory(ParserModule.java:124)
> > ... 146 more
> >

I find this getPackage()... business pointless. It's much better if the
code is just

   throw new UnsupportedOperationException("setXIncludeAware is not
supported on this JAXP 1.4 implementation or earlier: "+this.getClass());

An extra bonus point is to let the method work silently if the state is
false, since it's a no-op.

-- Kohsuke Kawaguchi http://weblogs.java.net/blog/kohsuke/