XWiki doesn't work on IBM JDK 1.6

Caused by: java.lang.NullPointerException
	at java.util.LinkedHashMap.putImpl(LinkedHashMap.java:412)
	at java.util.LinkedHashMap.put(LinkedHashMap.java:370)
	at org.infinispan.util.concurrent.BoundedConcurrentHashMap$LRU.onEntryMiss(BoundedConcurrentHashMap.java:459)
	at org.infinispan.util.concurrent.BoundedConcurrentHashMap$Segment.remove(BoundedConcurrentHashMap.java:1540)
	at org.infinispan.util.concurrent.BoundedConcurrentHashMap$LRU.removeEldestEntry(BoundedConcurrentHashMap.java:519)
	at java.util.LinkedHashMap.putImpl(LinkedHashMap.java:411)
	at java.util.LinkedHashMap.put(LinkedHashMap.java:370)
	at org.infinispan.util.concurrent.BoundedConcurrentHashMap$LRU.onEntryMiss(BoundedConcurrentHashMap.java:459)
	at org.infinispan.util.concurrent.BoundedConcurrentHashMap$Segment.remove(BoundedConcurrentHashMap.java:1540)
	at org.infinispan.util.concurrent.BoundedConcurrentHashMap$LRU.removeEldestEntry(BoundedConcurrentHashMap.java:519)
	at java.util.LinkedHashMap.putImpl(LinkedHashMap.java:411)
	at java.util.LinkedHashMap.put(LinkedHashMap.java:370)
	at org.infinispan.util.concurrent.BoundedConcurrentHashMap$LRU.onEntryMiss(BoundedConcurrentHashMap.java:459)
	at org.infinispan.util.concurrent.BoundedConcurrentHashMap$Segment.put(BoundedConcurrentHashMap.java:1423)
	at org.infinispan.util.concurrent.BoundedConcurrentHashMap.put(BoundedConcurrentHashMap.java:1989)
	at org.infinispan.container.DefaultDataContainer.put(DefaultDataContainer.java:153)
	at org.infinispan.container.entries.ReadCommittedEntry.commit(ReadCommittedEntry.java:198)
	at org.infinispan.interceptors.locking.ClusteringDependentLogic$AllNodesLogic.commitEntry(ClusteringDependentLogic.java:115)
	at org.infinispan.interceptors.EntryWrappingInterceptor.commitContextEntry(EntryWrappingInterceptor.java:208)
	at org.infinispan.interceptors.EntryWrappingInterceptor.commitEntryIfNeeded(EntryWrappingInterceptor.java:286)
	at org.infinispan.interceptors.EntryWrappingInterceptor.commitContextEntries(EntryWrappingInterceptor.java:187)
	at org.infinispan.interceptors.EntryWrappingInterceptor.invokeNextAndApplyChanges(EntryWrappingInterceptor.java:213)
	at org.infinispan.interceptors.EntryWrappingInterceptor.visitPutKeyValueCommand(EntryWrappingInterceptor.java:147)
	at org.infinispan.commands.write.PutKeyValueCommand.acceptVisitor(PutKeyValueCommand.java:77)
	at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:116)
	at org.infinispan.interceptors.locking.NonTransactionalLockingInterceptor.visitPutKeyValueCommand(NonTransactionalLockingInterceptor.java:68)
	at org.infinispan.commands.write.PutKeyValueCommand.acceptVisitor(PutKeyValueCommand.java:77)
	at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:116)
	at org.infinispan.interceptors.base.CommandInterceptor.handleDefault(CommandInterceptor.java:130)
	at org.infinispan.commands.AbstractVisitor.visitPutKeyValueCommand(AbstractVisitor.java:62)
	at org.infinispan.commands.write.PutKeyValueCommand.acceptVisitor(PutKeyValueCommand.java:77)
	at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:116)
	at org.infinispan.interceptors.CacheMgmtInterceptor.visitPutKeyValueCommand(CacheMgmtInterceptor.java:127)
	at org.infinispan.commands.write.PutKeyValueCommand.acceptVisitor(PutKeyValueCommand.java:77)
	at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:116)
	at org.infinispan.interceptors.InvocationContextInterceptor.handleAll(InvocationContextInterceptor.java:132)
	at org.infinispan.interceptors.InvocationContextInterceptor.handleDefault(InvocationContextInterceptor.java:91)
	at org.infinispan.commands.AbstractVisitor.visitPutKeyValueCommand(AbstractVisitor.java:62)
	at org.infinispan.commands.write.PutKeyValueCommand.acceptVisitor(PutKeyValueCommand.java:77)
	at org.infinispan.interceptors.InterceptorChain.invoke(InterceptorChain.java:345)
	at org.infinispan.CacheImpl.executeCommandAndCommitIfNeeded(CacheImpl.java:1006)
	at org.infinispan.CacheImpl.put(CacheImpl.java:702)
	at org.infinispan.CacheImpl.put(CacheImpl.java:694)
	at org.infinispan.CacheSupport.put(CacheSupport.java:53)
	at org.xwiki.cache.infinispan.internal.InfinispanCache.set(InfinispanCache.java:86)
	at com.xpn.xwiki.store.XWikiCacheStore.loadXWikiDoc(XWikiCacheStore.java:295)
	at com.xpn.xwiki.XWiki.getDocument(XWiki.java:1430)
	at com.xpn.xwiki.XWiki.getDocument(XWiki.java:1484)
	at com.xpn.xwiki.plugin.packaging.DocumentInfo.testInstall(DocumentInfo.java:127)
	at com.xpn.xwiki.plugin.packaging.Package.testInstall(Package.java:605)
	at com.xpn.xwiki.plugin.packaging.Package.install(Package.java:623)
	at com.xpn.xwiki.plugin.packaging.PackageAPI.install(PackageAPI.java:316)
	at com.xpn.xwiki.web.ImportAction.render(ImportAction.java:132)