Certain versions of openjdk contains a broken version of apache xmlsec which causes signatures to fail on xml documents with more than 23 namespace declarations:
- http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6696582
- https://issues.apache.org/bugzilla/show_bug.cgi?id=38655
If you run into this problem you will get an ArrayIndexOutOfBoundsException when you try to reference certain entities through the MDX interface.
The simplest workaround may be to use the SUN JDK but an alternative is to endorse a modern version of xmlsec which doesn't have the bug. Do this by creating a directory (anywhere) and add commons-logging-1.1.1.jar and xmlsec-1.4.3.jar to that directory. Now start the aggregator with -Djava.endorsed.dirs=/the/directory.