Storing String values using Kryo marshaller sometimes throws Index out of bounds warning:

WARN [org.radargun.stages.cache.test.LoadStage] (Loader-4) Attempt 1/10 to insert entry into cache failed, waiting 1000 ms before next attempt
java.lang.ArrayIndexOutOfBoundsException: 64
at com.esotericsoftware.kryo.util.IdentityObjectIntMap.putStash(IdentityObjectIntMap.java:310) ~[kryo-4.0.0.jar:?]
at com.esotericsoftware.kryo.util.IdentityObjectIntMap.push(IdentityObjectIntMap.java:298) ~[kryo-4.0.0.jar:?]
at com.esotericsoftware.kryo.util.IdentityObjectIntMap.put(IdentityObjectIntMap.java:161) ~[kryo-4.0.0.jar:?]
at com.esotericsoftware.kryo.util.MapReferenceResolver.addWrittenObject(MapReferenceResolver.java:41) ~[kryo-4.0.0.jar:?]
at com.esotericsoftware.kryo.Kryo.writeReferenceOrNull(Kryo.java:681) ~[kryo-4.0.0.jar:?]
at com.esotericsoftware.kryo.Kryo.writeClassAndObject(Kryo.java:646) ~[kryo-4.0.0.jar:?]
at org.infinispan.marshaller.kryo.KryoMarshaller.objectToBuffer(KryoMarshaller.java:58) ~[infinispan-marshaller-kryo-9.0.0-SNAPSHOT.jar:9.0.0-SNAPSHOT]
at org.infinispan.commons.marshall.AbstractMarshaller.objectToByteBuffer(AbstractMarshaller.java:70) ~[infinispan-commons-9.0.0-SNAPSHOT.jar:9.0.0-SNAPSHOT]
at org.infinispan.client.hotrod.impl.RemoteCacheImpl.obj2bytes(RemoteCacheImpl.java:498) ~[infinispan-client-hotrod-9.0.0-SNAPSHOT.jar:9.0.0-SNAPSHOT]
at org.infinispan.client.hotrod.impl.RemoteCacheImpl.put(RemoteCacheImpl.java:270) ~[infinispan-client-hotrod-9.0.0-SNAPSHOT.jar:9.0.0-SNAPSHOT]
at org.infinispan.client.hotrod.impl.RemoteCacheSupport.put(RemoteCacheSupport.java:79) ~[infinispan-client-hotrod-9.0.0-SNAPSHOT.jar:9.0.0-SNAPSHOT]
at org.radargun.service.HotRodOperations$HotRodCache.put(HotRodOperations.java:83) ~[plugin-infinispan52-3.0.0-SNAPSHOT.jar:?]
at org.radargun.stages.cache.test.LoadStage$NonTxLoader.loadDataUnit(LoadStage.java:275) [radargun-cache-3.0.0-SNAPSHOT.jar:?]
at org.radargun.stages.test.LoadStage$Loader.run(LoadStage.java:125) [radargun-core-3.0.0-SNAPSHOT.jar:?