This works fine with jre1.6.0 build 47, but failed with b48PIT

Steps to reproduce :
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1. Install mustang JRE b48PIT from http://j2se.east/arc/1.6.0/pit/2005-08-16/windows-i586/
(jre-6_0-fcs-bin-b99-windows-i586-16_aug_2005.exe)
2. Clear cache using javaws -uninstall
3. Import a jnlp with <component-desc/> element using command ,
javaws -import http://sceri.prc/~yl153753/cacheViewer/CacheViewer_Library.jnlp

It will throw the following exception :
java.lang.NullPointerException
at com.sun.javaws.Launcher.prepareLaunchFile(Unknown Source)
at com.sun.javaws.Launcher.prepareToLaunch(Unknown Source)
at com.sun.javaws.Launcher.launch(Unknown Source)
at com.sun.javaws.Main.launchApp(Unknown Source)
at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
at com.sun.javaws.Main$1.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
And the console shows error :
----------------------------------------------------
#### Java Web Start Error:
#### null