NPE in OutboundQueueManager while flushing entry

2015-06-05 16:19:58,158 | WARN | entLoopGroup-6-5 | SingleThreadEventExecutor | 116 - io.netty.common - 4.0.26.Final | A task raised an exception.
java.lang.NullPointerException
at org.opendaylight.openflowjava.protocol.impl.core.connection.OutboundQueueManager.flushEntry(OutboundQueueManager.java:169)[192:org.opendaylight.openflowjava.openflow-protocol-impl:0.6.0.SNAPSHOT]
at org.opendaylight.openflowjava.protocol.impl.core.connection.OutboundQueueManager.flush(OutboundQueueManager.java:341)[192:org.opendaylight.openflowjava.openflow-protocol-impl:0.6.0.SNAPSHOT]
at org.opendaylight.openflowjava.protocol.impl.core.connection.OutboundQueueManager$1.run(OutboundQueueManager.java:67)[192:org.opendaylight.openflowjava.openflow-protocol-impl:0.6.0.SNAPSHOT]
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:328)[116:io.netty.common:4.0.26.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:350)[115:io.netty.transport:4.0.26.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:111)[116:io.netty.common:4.0.26.Final]
at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:137)[116:io.netty.common:4.0.26.Final]