It appears to be a signature bug in the JAXP 1.4 build 'h1164' due to the fix for 6861589.

(The problem was encountered while running the JDK 6u18 "2009-10-12-060623.wsmgr.j2se" build taken from [1] for testing the JCK 6b alternative bundle).

I've run the JCK 6b signature test with the installed JCK 6b alt bundle promoted build [2] and gotten the following error:

====================================

Missing Methods
---------------

javax.xml.stream.XMLOutputFactory: method public static
javax.xml.stream.XMLOutputFactory
javax.xml.stream.XMLOutputFactory.newFactory(java.lang.String,java.lang.ClassLoader)

Added Methods
-------------

javax.xml.stream.XMLOutputFactory: method public static
javax.xml.stream.XMLInputFactory
javax.xml.stream.XMLOutputFactory.newFactory(java.lang.String,java.lang.ClassLoader)

====================================

As you can see the new XMLOutputFactory.newFactory(String, ClassLoader) method
of the JDK 6u18 returns the XMLInputFactory type that contradicts to p. 4 of the
StAX 1.2 specification [3]. The method must return the XMLOutputFactory type
instead.

I've checked that the source file javax/xml/stream/XMLOutputFactory.java from
Oracle, you recieved from the JAXP team some time ago, and the corresponding source file from the JDK source bundle, taken from the jprt, doesn't match in terms of the method signature.

[1] /net/prt-archiver.sfbay.sun.com/data/jprt/archive/2009/10
[2] /java/re/jck/6b/alt01/bundles/latest
[3] http://ccc.sfbay/2180205/attachment/jsr173MR3.htm