NPE in MarkSweepGarbageCollector.saveBatchToFile during Datastore GC with FileDataStore

13.05.2014 17:50:16.944 *ERROR* [qtp1416657193-147] org.apache.jackrabbit.oak.management.ManagementOperation Blob garbage collection failed
java.lang.RuntimeException: Error in retrieving references
	at org.apache.jackrabbit.oak.plugins.blob.MarkSweepGarbageCollector$1.addReference(MarkSweepGarbageCollector.java:395)
	at org.apache.jackrabbit.oak.plugins.segment.Segment.collectBlobReferences(Segment.java:248)
	at org.apache.jackrabbit.oak.plugins.segment.SegmentTracker.collectBlobReferences(SegmentTracker.java:178)
	at org.apache.jackrabbit.oak.plugins.segment.SegmentBlobReferenceRetriever.collectReferences(SegmentBlobReferenceRetriever.java:38)
	at org.apache.jackrabbit.oak.plugins.blob.MarkSweepGarbageCollector.iterateNodeTree(MarkSweepGarbageCollector.java:361)
	at org.apache.jackrabbit.oak.plugins.blob.MarkSweepGarbageCollector.mark(MarkSweepGarbageCollector.java:201)
	at org.apache.jackrabbit.oak.plugins.blob.MarkSweepGarbageCollector.markAndSweep(MarkSweepGarbageCollector.java:173)
	at org.apache.jackrabbit.oak.plugins.blob.MarkSweepGarbageCollector.collectGarbage(MarkSweepGarbageCollector.java:149)
	at org.apache.jackrabbit.oak.plugins.segment.SegmentNodeStoreService$2.collectGarbage(SegmentNodeStoreService.java:185)
	at org.apache.jackrabbit.oak.plugins.blob.BlobGC$1.call(BlobGC.java:68)
	at org.apache.jackrabbit.oak.plugins.blob.BlobGC$1.call(BlobGC.java:64)
	at java.util.concurrent.FutureTask.run(FutureTask.java:262)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException: null
	at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:192)
	at com.google.common.base.Joiner.toString(Joiner.java:436)
	at com.google.common.base.Joiner.appendTo(Joiner.java:108)
	at com.google.common.base.Joiner.appendTo(Joiner.java:152)
	at com.google.common.base.Joiner.join(Joiner.java:193)
	at com.google.common.base.Joiner.join(Joiner.java:183)
	at org.apache.jackrabbit.oak.plugins.blob.MarkSweepGarbageCollector.saveBatchToFile(MarkSweepGarbageCollector.java:317)
	at org.apache.jackrabbit.oak.plugins.blob.MarkSweepGarbageCollector$1.addReference(MarkSweepGarbageCollector.java:391)
	... 14 common frames omitted