ClassCastException if cache.keyset() is invoked for a string-keyed-jdbc-store in C/S mode

If the cache is empty cache.keyset() invocation returns an empty set.
If it is invoked after entities are added it failes with the Exception below.
The same test work if a binary-keyed-jdbc-store is used!

The HotRod client is based on the hot-rod C/S quickstart.

The configuration is:
<subsystem xmlns="urn:infinispan:server:core:6.0" default-cache-container="clustered">
<cache-container name="clustered" default-cache="string" statistics="true">
<transport executor="infinispan-transport" lock-timeout="60000"/>

<replicated-cache name="string" mode="ASYNC" start="EAGER">
<locking isolation="READ_COMMITTED" acquire-timeout="20000" concurrency-level="500" striping="false"/>
<transaction mode="NONE"/>
<string-keyed-jdbc-store datasource="java:jboss/datasources/JDGDatasource" passivation="false" preload="true" purge="false" shared="false">
<!-- property name="databaseType">ORACLE</property -->
<string-keyed-table prefix="qs">
<id-column name="id" type="VARCHAR(255)"/>
<data-column name="datum" type="BLOB(2000)"/>
<timestamp-column name="version" type="BIGINT"/>
</string-keyed-table>
<write-behind modification-queue-size="1024" shutdown-timeout="25000" flush-lock-timeout="15000" thread-pool-size="5" />
</string-keyed-jdbc-store>
<expiration interval="10000" />
</replicated-cache>

ERROR [org.infinispan.server.hotrod.HotRodDecoder:76] (HotRodServerWorker-88) ISPN005009: Unexpected error before any request parameters read: java.lang.ClassCastException: java.lang.String cannot be cast to [B
at org.infinispan.server.hotrod.AbstractEncoder1x$$anonfun$writeResponse$5.apply(AbstractEncoder1x.scala:113) [infinispan.jar:7.0.0-SNAPSHOT]
at scala.collection.Iterator$class.foreach(Iterator.scala:727)
at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
at org.infinispan.server.hotrod.AbstractEncoder1x.writeResponse(AbstractEncoder1x.scala:113) [infinispan.jar:7.0.0-SNAPSHOT]
at org.infinispan.server.hotrod.HotRodEncoder.encode(HotRodEncoder.scala:48) [infinispan.jar:7.0.0-SNAPSHOT]
at org.jboss.netty.handler.codec.oneone.OneToOneEncoder.doEncode(OneToOneEncoder.java:66) [netty-3.6.6.Final.jar:]
at org.jboss.netty.handler.codec.oneone.OneToOneEncoder.handleDownstream(OneToOneEncoder.java:59) [netty-3.6.6.Final.jar:]
at org.jboss.netty.channel.Channels.write(Channels.java:704) [netty-3.6.6.Final.jar:]
at org.jboss.netty.channel.Channels.write(Channels.java:671) [netty-3.6.6.Final.jar:]
at org.jboss.netty.channel.AbstractChannel.write(AbstractChannel.java:248) [netty-3.6.6.Final.jar:]
at org.infinispan.server.core.AbstractProtocolDecoder.writeResponse(AbstractProtocolDecoder.scala:163) [infinispan.jar:7.0.0-SNAPSHOT]
at org.infinispan.server.hotrod.HotRodDecoder.customDecodeKey(HotRodDecoder.scala:138) [infinispan.jar:7.0.0-SNAPSHOT]
at org.infinispan.server.core.AbstractProtocolDecoder.decodeKey(AbstractProtocolDecoder.scala:105) [infinispan.jar:7.0.0-SNAPSHOT]
at org.infinispan.server.core.AbstractProtocolDecoder.decode(AbstractProtocolDecoder.scala:53) [infinispan.jar:7.0.0-SNAPSHOT]
at org.infinispan.server.core.AbstractProtocolDecoder.decode(AbstractProtocolDecoder.scala:29) [infinispan.jar:7.0.0-SNAPSHOT]
at org.jboss.netty.handler.codec.replay.ReplayingDecoder.callDecode(ReplayingDecoder.java:500) [netty-3.6.6.Final.jar:]
at org.jboss.netty.handler.codec.replay.ReplayingDecoder.messageReceived(ReplayingDecoder.java:435) [netty-3.6.6.Final.jar:]
at org.infinispan.server.core.AbstractProtocolDecoder.messageReceived(AbstractProtocolDecoder.scala:377) [infinispan.jar:7.0.0-SNAPSHOT]
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:268) [netty-3.6.6.Final.jar:]
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:255) [netty-3.6.6.Final.jar:]
at org.jboss.netty.channel.socket.nio.NioWorker.read(NioWorker.java:88) [netty-3.6.6.Final.jar:]
at org.jboss.netty.channel.socket.nio.AbstractNioWorker.process(AbstractNioWorker.java:109) [netty-3.6.6.Final.jar:]
at org.jboss.netty.channel.socket.nio.AbstractNioSelector.run(AbstractNioSelector.java:312) [netty-3.6.6.Final.jar:]
at org.jboss.netty.channel.socket.nio.AbstractNioWorker.run(AbstractNioWorker.java:90) [netty-3.6.6.Final.jar:]
at org.jboss.netty.channel.socket.nio.NioWorker.run(NioWorker.java:178) [netty-3.6.6.Final.jar:]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [rt.jar:1.7.0_51]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [rt.jar:1.7.0_51]
at java.lang.Thread.run(Thread.java:744) [rt.jar:1.7.0_51]