OpenSAML bootstrap() nets me “InputStream cannot be null”

Question

Deployment environment: Windows Server 2008, Tomcat 7.0.5, Oracle JRE 1.6. Development environment same plus Eclipse Helios.

When I try to deploy my Java application which uses OpenSAML 2.3.1 and test it live, it doesn't want to run. Looking through the source code and stack trace, it seems that DefaultBootstrap.bootstrap() ends up causing java.lang.IllegalArgumentException: InputStream cannot be null. I'm including the full stack trace below.

The software versions on the target deployment system are, or at least are supposed to be, exactly the same as on my development box, where everything runs just fine, but of course there I don't deploy using the .war. I am getting the distinct feeling that I'm missing some XML or DTD file in the deployment archive, but that feeling alone doesn't help me much in fixing it. Googling for parts of the stacktrace also didn't really help me much.

Where do I start tracking down the actual root cause of this error, so I can fix it?

2011-feb-10 10:56:08 org.apache.catalina.core.StandardWrapperValve invoke
ALLVARLIG: Servlet.service() for servlet [se.novasoftware.gabriel.SAMLParser] in context with path [/ServiceTier] threw exception [java.lang.IllegalArgumentException: InputStream cannot be null] with root cause
java.lang.IllegalArgumentException: InputStream cannot be null
at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:120)
at org.opensaml.xml.parse.BasicParserPool$DocumentBuilderProxy.parse(BasicParserPool.java:643)
at org.opensaml.xml.parse.BasicParserPool.parse(BasicParserPool.java:216)
at org.opensaml.xml.XMLConfigurator.load(XMLConfigurator.java:141)
at org.opensaml.DefaultBootstrap.initializeXMLTooling(DefaultBootstrap.java:148)
at org.opensaml.DefaultBootstrap.bootstrap(DefaultBootstrap.java:88)
at _mynamespace_.saml.ParsedResponse.<init>(ParsedResponse.java:56)
at _mynamespace_.saml.ParsedResponse.<init>(ParsedResponse.java:104)
at _mynamespace_.SAMLParser.doPost(SAMLParser.java:29) // servlet entry point
at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:306)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:108)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:379)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:259)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:281)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)

ParsedResponse.java line 56 is the bootstrap() call in its constructor:

private PersedResponse() throws ConfigurationException {
    DefaultBootstrap.bootstrap(); // line 56
    ...

whereas line 104 in that same file is the constructor that gets called from the outside calling this private default constructor:

public ParsedResponse(final String samlXML)
        throws UnmarshallingException, ConfigurationException {
    this(); // line 104
    ...