Accessing arbitrary XPCOM interfaces using JavaXPCOM

Hello, I'm using a XULRunner I built from source pulled with cvs tag
FIREFOX_2_0_0_3_RELEASE.  I'm trying to use firebug from my embedding
app using Java XPCOM.  I have verified that I can successfully access
the nsIFireBug service from native code by verifying that rv == 0 in
the
following:

C++ Example:

01.  nsCOMPtr<nsIFireBug> fireBug = do_GetService("@joehewitt.com/
firebug;1",
02.                                               &rv);
03.  if (NS_FAILED(rv)) {
04.        ::util_ThrowExceptionToJava(env, "Failed to get FireBug
Service");
05.  }

I used xpidl -m java to produce java interfaces from the
nsIFireBug.idl
file, and compiled these interfaces into MozillaInterfaces.jar, like
this:

jar -tf MozillaInterfaces.jar | grep FireBug
org/mozilla/interfaces/nsIFireBug.class
org/mozilla/interfaces/nsIFireBugBreakpointCallback.class
org/mozilla/interfaces/nsIFireBugClient.class
org/mozilla/interfaces/nsIFireBugDebugger.class

I put this MozillaInterfaces.jar and javaxpcom.jar on my app
classpath.

However, when I do the following from my Java code:

Java Example:

01. org.mozilla.xpcom.Mozilla mozilla =
org.mozilla.xpcom.Mozilla.getInstance();
02. mozilla.initialize(new File("F:\Projects\mozilla\MOZILLA_NIH
\FIREFOX_2_0_0_3_RELEASE\mozilla\xulrunner-win32_d.obj\dist\bin"));
03. nsIServiceManager srvMan = mozilla.getServiceManager();
04. nsIObserverService observerService =
05.     (nsIObserverService)
srvMan.getServiceByContractID("@mozilla.org/observer-service;1",
06.     "d07f5192-e3d1-11d2-8acd-00105a1b8860");
07. nsIFireBug firebug = (nsIFireBug)
08.       srvMan.getServiceByContractID("@joehewitt.com/firebug;1",
"f71f61b2-cb37-11da-9b41-b622a1ef5492");

When line 08 executes, I get this exception.

Exception in thread "foo" org.mozilla.xpcom.XPCOMException: The
function "getServiceByContractID" returned an error condition
(0x8000ffff)
        at
org.mozilla.xpcom.internal.XPCOMJavaProxy.callXPCOMMethod(Native
Method)
        at
org.mozilla.xpcom.internal.XPCOMJavaProxy.invoke(XPCOMJavaProxy.java:
143)
        at $Proxy0.getServiceByContractID(Unknown Source)
        at org.mozilla.webclient.impl.wrapper_native.WrapperFactoryImpl
$3.run(WrapperFactoryImpl.java:390)
        at
org.mozilla.webclient.impl.wrapper_native.NativeEventThread.run(NativeEventThread.java:
162)

Considering that the C++ Example works, but the Java Example does not,
I
must be missing something fundamental.

Can anyone shed light on this?  Javier?

Ed