Caused by: java.util.ConcurrentModificationException
        at java.util.Hashtable$Enumerator.next(Hashtable.java:1020)
        at org.snmp4j.Snmp.close(Unknown Source)
        at org.opennms.netmgt.snmp.snmp4j.Snmp4JWalker.close(Snmp4JWalker.java:223)
        at org.opennms.netmgt.snmp.SnmpWalker.finish(SnmpWalker.java:149)
        at org.opennms.netmgt.snmp.SnmpWalker.handleFatalError(SnmpWalker.java:136)
        at org.opennms.netmgt.snmp.snmp4j.Snmp4JWalker.access$700(Snmp4JWalker.java:58)
        at org.opennms.netmgt.snmp.snmp4j.Snmp4JWalker$Snmp4JResponseListener.processResponse(Snmp4JWalker.java:151)
        at org.opennms.netmgt.snmp.snmp4j.Snmp4JWalker$Snmp4JResponseListener.onResponse(Snmp4JWalker.java:167)
        at org.snmp4j.Snmp.processPdu(Unknown Source)
        at org.snmp4j.MessageDispatcherImpl.fireProcessPdu(Unknown Source)
        at org.snmp4j.MessageDispatcherImpl.dispatchMessage(Unknown Source)