NullPointer when starting org.apache.felix.http.jetty-2.0.4 bundle

When starting the org.apache.felix.http.jetty-2.0.4 bundle a NullPointerException is thrown by "org.apache.felix.framework.util.StringComparator.compare(StringComparator.java:40)"...

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config.properties
—
felix.auto.deploy.action=disabled
org.osgi.framework.startlevel.beginning=1
felix.auto.start.1=file:bundle/org.apache.felix.bundlerepository-1.6.2.jar file:bundle/org.apache.felix.gogo.command-0.6.0.jar file:bundle/org.apache.felix.gogo.runtime-0.6.0.jar file:bundle org.apache.felix.gogo.shell-0.6.0.jar file:bundle/org.osgi.compendium-1.4.0.jar file:bundle/jetty-6.1.24.jar file:bundle/jetty-util-6.1.24.jar file:bundle/servlet-api-2.5.jar file:bundle/org.apache.felix.http.api-2.0.4.jar file:bundle/org.apache.felix.http.base-2.0.4.jar
felix.auto.start.2=file:bundle/org.apache.felix.http.jetty-2.0.4.jar
felix.auto.start.3=file:bundle/testproject-0.1.jar

Level1 works fine so far, but when I switch to level2 the following Exception is thrown:

ERROR: EventDispatcher: Error during dispatch. (java.lang.NullPointerException)
java.lang.NullPointerException
at org.apache.felix.framework.util.StringComparator.compare(StringComparator.java:40)
at java.util.TreeMap.getEntryUsingComparator(Unknown Source)
at java.util.TreeMap.getEntry(Unknown Source)
at java.util.TreeMap.get(Unknown Source)
at org.apache.felix.framework.util.StringMap.get(StringMap.java:88)
at org.apache.felix.framework.util.MapToDictionary.get(MapToDictionary.java:51)
at org.apache.felix.framework.FilterImpl$DictionaryCapability.getAttribute(FilterImpl.java:147)
at org.apache.felix.framework.capabilityset.CapabilitySet.matchesInternal(CapabilitySet.java:269)
at org.apache.felix.framework.capabilityset.CapabilitySet.matchesInternal(CapabilitySet.java:242)
at org.apache.felix.framework.capabilityset.CapabilitySet.matches(CapabilitySet.java:226)
at org.apache.felix.framework.FilterImpl.match(FilterImpl.java:59)
at org.apache.felix.framework.util.EventDispatcher.invokeServiceListenerCallback(EventDispatcher.java:872)
at org.apache.felix.framework.util.EventDispatcher.fireEventImmediately(EventDispatcher.java:732)
at org.apache.felix.framework.util.EventDispatcher.fireServiceEvent(EventDispatcher.java:662)
at org.apache.felix.framework.Felix.fireServiceEvent(Felix.java:3745)
at org.apache.felix.framework.Felix.access$000(Felix.java:80)
at org.apache.felix.framework.Felix$2.serviceChanged(Felix.java:717)
at org.apache.felix.framework.ServiceRegistry.servicePropertiesModified(ServiceRegistry.java:478)
at org.apache.felix.framework.ServiceRegistrationImpl.setProperties(ServiceRegistrationImpl.java:116)
at org.apache.felix.http.base.internal.HttpServiceController.setProperties(HttpServiceController.java:56)
at org.apache.felix.http.jetty.internal.JettyService.publishServiceProperties(JettyService.java:96)
at org.apache.felix.http.jetty.internal.JettyService.initializeJetty(JettyService.java:146)
at org.apache.felix.http.jetty.internal.JettyService.startJetty(JettyService.java:112)
at org.apache.felix.http.jetty.internal.JettyService.run(JettyService.java:203)
at java.lang.Thread.run(Unknown Source)
[INFO] Started jetty 6.1.x at port 8080