I get this exception at each NetBeans startup:

java.lang.NullPointerException
	at org.eclipse.core.internal.net.ProxyManager.getPluggedInAuthenticator(ProxyManager.java:390)
	at org.eclipse.core.internal.net.ProxyManager.registerAuthenticator(ProxyManager.java:383)
	at org.eclipse.core.internal.net.ProxyManager.initialize(ProxyManager.java:284)
	at org.eclipse.core.internal.net.Activator.start(Activator.java:179)
	at org.eclipse.osgi.framework.internal.core.BundleContextImpl$1.run(BundleContextImpl.java:711)
	at java.security.AccessController.doPrivileged(Native Method)
	at org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:702)
Caused: org.osgi.framework.BundleException: Exception in org.eclipse.core.internal.net.Activator.start() of bundle org.eclipse.core.net.
	at org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:734)
	at org.eclipse.osgi.framework.internal.core.BundleContextImpl.start(BundleContextImpl.java:683)
	at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:381)
	at org.eclipse.osgi.framework.internal.core.AbstractBundle.start(AbstractBundle.java:299)
	at org.eclipse.osgi.framework.util.SecureAction.start(SecureAction.java:440)
	at org.eclipse.osgi.internal.loader.BundleLoader.setLazyTrigger(BundleLoader.java:268)
	at org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:107)
Caused: org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter$TerminatingClassNotFoundException: An error occurred while automatically activating bundle org.eclipse.core.net (106).
	at org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:122)
	at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findLocalClass(ClasspathManager.java:462)
	at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.findLocalClass(DefaultClassLoader.java:216)
	at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:400)
	at org.eclipse.osgi.internal.loader.SingleSourcePackage.loadClass(SingleSourcePackage.java:35)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:473)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:429)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:417)
	at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
Caused: java.lang.NoClassDefFoundError: org/eclipse/core/net/proxy/IProxyService
	at org.eclipse.mylyn.internal.commons.net.CommonsNetPlugin.start(CommonsNetPlugin.java:91)
	at org.eclipse.osgi.framework.internal.core.BundleContextImpl$1.run(BundleContextImpl.java:711)
	at java.security.AccessController.doPrivileged(Native Method)
	at org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:702)
Caused: org.osgi.framework.BundleException: Exception in org.eclipse.mylyn.internal.commons.net.CommonsNetPlugin.start() of bundle org.eclipse.mylyn.commons.net.
	at org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:734)
	at org.eclipse.osgi.framework.internal.core.BundleContextImpl.start(BundleContextImpl.java:683)
	at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:381)
	at org.eclipse.osgi.framework.internal.core.AbstractBundle.resume(AbstractBundle.java:389)
	at org.eclipse.osgi.framework.internal.core.Framework.resumeBundle(Framework.java:1131)
	at org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:559)
	at org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:544)
	at org.eclipse.osgi.framework.internal.core.StartLevelManager.incFWSL(StartLevelManager.java:457)
	at org.eclipse.osgi.framework.internal.core.StartLevelManager.doSetStartLevel(StartLevelManager.java:243)
	at org.eclipse.osgi.framework.internal.core.EquinoxLauncher.internalStart(EquinoxLauncher.java:271)
	at org.eclipse.osgi.framework.internal.core.EquinoxLauncher.start(EquinoxLauncher.java:241)
	at org.eclipse.osgi.launch.Equinox.start(Equinox.java:258)
	at org.netbeans.core.netigso.Netigso.start(Netigso.java:187)
	at org.netbeans.NetigsoHandle.startFramework(NetigsoHandle.java:196)
	at org.netbeans.ModuleManager.enable(ModuleManager.java:1180)
	at org.netbeans.ModuleManager.enable(ModuleManager.java:1002)
	at org.netbeans.core.startup.ModuleList.installNew(ModuleList.java:340)
	at org.netbeans.core.startup.ModuleList.trigger(ModuleList.java:276)
	at org.netbeans.core.startup.ModuleSystem.restore(ModuleSystem.java:296)
	at org.netbeans.core.startup.Main.getModuleSystem(Main.java:169)
	at org.netbeans.core.startup.Main.start(Main.java:305)
	at org.netbeans.core.startup.TopThreadGroup.run(TopThreadGroup.java:123)
[catch] at java.lang.Thread.run(Thread.java:722)


Clean NB installation and profile, NB7.2.1 (full distro) on JDK7u09 (tested on JDK6u37 too) on Windows7 x86_32.

Could you take a look at this ? Thx.

Created attachment 129223 [details]
NB logs.

Added NB logs.

I get the same exception, nevertheless there is no influence on Netbeans or plugin functionality. In my system, the exception is logged in the system log only, no interaction with users takes place.

According to the attached log, the plugin is loaded. If you start Javahelp (press F1), plugin should recognize the component and install Swingbox viewer (appearance of the browsed content should change after a short while). 

Browsing experience with Netbeans Help is not goot because of CSS problems - missing units (px) in style.css used by Netbeans. Plugin is primarily dedicated to be embedded into RCP applications.

When the plugin is embedded into any of my RCP application, the reported exception does not appear. Most probably, it is caused by a conflict with a Netbeans plugin which is part of the full Netbeans installation? I do not use OSGI, so I could not recognize influence on it.

On my test machine, the exception is also displayed in a pop-up window.
This is why I can't validate the plugin.

*** Bug 223715 has been marked as a duplicate of this bug. ***

Product Version: NetBeans IDE 7.2.1 (Build 201210100934)
Java: 1.7.0_10-ea; Java HotSpot(TM) 64-Bit Server VM 23.6-b04
System: Linux version 3.0.0-12-generic running on amd64; UTF-8; cs_CZ (nb)
User directory: /home/cesilko/.netbeans/7.2.1
Cache directory: /home/cesilko/.cache/netbeans/7.2.1

I got the same exception. Frantisku, can you please fix it?

The source of the problem was found in duplicate presence of XercesImpl plugin.

New issue was created upstream at the plugin hosting project:

https://code.google.com/p/swingbox-javahelp-viewer/issues/detail?id=1

Proposed solution:

When installing JHelpContentViewerUI, modify JEditorPane creation following these steps:

- Put XercesImpl as provided dependency only, do not include Xerces library with the plugin.

- Create new classloader which combines swingbox-javahelp-viewer module classloader with xerces module class loader and load BrowserPane implementation via reflection with the use of the combined classloader.

- Create BrowserPane instance and plug it into JHelpContentViewer

instead of simple instantiation of BrowserPane.

Fix is available at the upstream source repository:

http://code.google.com/p/swingbox-javahelp-viewer/source/detail?r=d8eab410a66b

Binary at plugins.netbeans.org was replaced with the new version 1.0.1.

New version works fine. Thx for the fix!

Professional cooperation guys. Thank you!