NPE in DistributedSegmentReadLocker

java.lang.NullPointerException
	at org.infinispan.lucene.readlocks.DistributedSegmentReadLocker.realFileDelete(DistributedSegmentReadLocker.java:184)
	at org.infinispan.lucene.readlocks.DistributedSegmentReadLocker.deleteOrReleaseReadLock(DistributedSegmentReadLocker.java:109)
	at org.infinispan.lucene.InfinispanDirectory.deleteFile(InfinispanDirectory.java:213)
	at org.apache.lucene.index.IndexFileDeleter.deleteFile(IndexFileDeleter.java:578)

final int bufferSize = file.getBufferSize();
if (file != null) //during optimization of index a same file could be deleted twice, so you could see a null here
......