if you configure thresholds for NSClient datacollection you get in collectd "An undeclared throwable" and "Null collection timestamp when thresholding service NSClientpp".

No thresholds events are generated.

Datacollection is working fine - see in collectd.log:
2014-04-01 11:52:02,398 INFO [Collectd-Thread-2-of-50] RrdUtils: updateRRD: updating RRD file /var/lib/opennms/rrd/snmp/1/cpuProcTime.jrb with values '1396345922:6.2524'
2014-04-01 11:52:02,402 INFO [Collectd-Thread-2-of-50] RrdUtils: updateRRD: updating RRD file /var/lib/opennms/rrd/snmp/1/cpuPrivTime.jrb with values '1396345922:4.68738'
2014-04-01 11:52:02,403 INFO [Collectd-Thread-2-of-50] RrdUtils: updateRRD: updating RRD file /var/lib/opennms/rrd/snmp/1/cpuIntrTime.jrb with values '1396345922:0'
2014-04-01 11:52:02,405 INFO [Collectd-Thread-2-of-50] RrdUtils: updateRRD: updating RRD file /var/lib/opennms/rrd/snmp/1/cpuUserTime.jrb with values '1396345922:0'

collectd-configuration.xml:
<package name="NSClient">
<filter>IPADDR IPLIKE ...</filter>
<service name="NSClientpp" interval="300000" user-defined="false" status="on">
<parameter key="nsclient-collection" value="default"/>
<parameter key="thresholding-enabled" value="true"/>
<parameter key="port" value="12489"/>
<parameter key="retry" value="3"/>
<parameter key="timeout" value="3000"/>
</service>
</package>
...
<collector service="NSClientpp" class-name="org.opennms.protocols.nsclient.collector.NSClientCollector"/>

nsclient-datacollection-config.xml (sorry - german system):
<wpms>
<!-- german -->
<wpm name="ProcessorProc" keyvalue="\Prozessor(_Total)\Prozessorzeit (%)" recheckInterval="3600000">
<attrib name="\Prozessor(_Total)\Prozessorzeit (%)" alias="cpuProcTime" type="Gauge"/>
</wpm>
<wpm name="ProcessorInt" keyvalue="\Prozessor(_Total)\Prozessorzeit (%)" recheckInterval="3600000">
<attrib name="\Prozessor(_Total)\Interruptzeit (%)" alias="cpuIntrTime" type="Gauge"/>
</wpm>
<wpm name="ProcessorPriv" keyvalue="\Prozessor(_Total)\Prozessorzeit (%)" recheckInterval="3600000">
<attrib name="\Prozessor(_Total)\Privilegierte Zeit (%)" alias="cpuPrivTime" type="Gauge"/>
</wpm>
<wpm name="ProcessorUser" keyvalue="\Prozessor(_Total)\Prozessorzeit (%)" recheckInterval="3600000">
<attrib name="\Prozessor(_Total)\Benutzerzeit (%)" alias="cpuUserTime" type="Gauge"/>
</wpm>
</wpms>

poller-configuration.xml:
<service name="NSClientpp" interval="300000" user-defined="false" status="on">
<parameter key="retry" value="2"/>
<parameter key="port" value="12489"/>
<parameter key="timeout" value="3000"/>
</service>
...
<monitor service="NSClientpp" class-name="org.opennms.netmgt.poller.monitors.NsclientMonitor"/>

threshd-configuration.xml:
<package name="NSClient">
<filter>IPADDR != '0.0.0.0'</filter>
<include-range begin="1.1.1.1" end="254.254.254.254"/>
<include-range begin="::1" end="ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff" />
<service name="NSClientpp" interval="300000" user-defined="false" status="on">
<parameter key="thresholding-group" value="NSClientpp"/>
</service>
</package>

thresholds.xml:
<group name="NSClientpp" rrdRepository="/var/lib/opennms/rrd/snmp/">
<threshold type="high" ds-type="node" value="2.0" rearm="0.0"
trigger="1" filterOperator="or" ds-name="cpuProcTime"/>
</group>

collectd.log:
2014-04-01 11:51:54,334 INFO [Collectd-Thread-2-of-50] CollectableService: run: starting new collection for 10.10.10.8/NSClientpp/NSClient
2014-04-01 11:51:54,338 DEBUG [Collectd-Thread-2-of-50] NSClientCollector: Checking availability of group ProcessorProc
2014-04-01 11:51:55,334 DEBUG [Collectd-Thread-2-of-50] NSClientCollector: Group ProcessorProc is available
2014-04-01 11:51:56,333 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:51:56,333 DEBUG [Collectd-Thread-2-of-50] NSClientCollector$NSClientCollectionResource: Adding attribute org.opennms.protocols.nsclient.collector.NSClientCollector$NSClientCollectionAttribute: NSClientCollectionAttribute cpuProcTime=6.2524 to group AttrGroupType[name=ProcessorProc, ifType=all] for null@1
2014-04-01 11:51:56,333 DEBUG [Collectd-Thread-2-of-50] NSClientCollector: Checking availability of group ProcessorInt
2014-04-01 11:51:57,346 DEBUG [Collectd-Thread-2-of-50] NSClientCollector: Group ProcessorInt is available
2014-04-01 11:51:58,345 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:51:58,345 DEBUG [Collectd-Thread-2-of-50] NSClientCollector$NSClientCollectionResource: Adding attribute org.opennms.protocols.nsclient.collector.NSClientCollector$NSClientCollectionAttribute: NSClientCollectionAttribute cpuIntrTime=0 to group AttrGroupType[name=ProcessorInt, ifType=all] for null@1
2014-04-01 11:51:58,345 DEBUG [Collectd-Thread-2-of-50] NSClientCollector: Checking availability of group ProcessorPriv
2014-04-01 11:51:59,360 DEBUG [Collectd-Thread-2-of-50] NSClientCollector: Group ProcessorPriv is available
2014-04-01 11:52:00,376 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:00,376 DEBUG [Collectd-Thread-2-of-50] NSClientCollector$NSClientCollectionResource: Adding attribute org.opennms.protocols.nsclient.collector.NSClientCollector$NSClientCollectionAttribute: NSClientCollectionAttribute cpuPrivTime=4.68738 to group AttrGroupType[name=ProcessorPriv, ifType=all] for null@1
2014-04-01 11:52:00,376 DEBUG [Collectd-Thread-2-of-50] NSClientCollector: Checking availability of group ProcessorUser
2014-04-01 11:52:01,393 DEBUG [Collectd-Thread-2-of-50] NSClientCollector: Group ProcessorUser is available
2014-04-01 11:52:02,392 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,392 DEBUG [Collectd-Thread-2-of-50] NSClientCollector$NSClientCollectionResource: Adding attribute org.opennms.protocols.nsclient.collector.NSClientCollector$NSClientCollectionAttribute: NSClientCollectionAttribute cpuUserTime=0 to group AttrGroupType[name=ProcessorUser, ifType=all] for null@1
2014-04-01 11:52:02,393 INFO [Collectd-Thread-2-of-50] OneToOnePersister: Persisting data for resource org.opennms.protocols.nsclient.collector.NSClientCollector$NSClientCollectionResource@2cd010f8
2014-04-01 11:52:02,394 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,394 DEBUG [Collectd-Thread-2-of-50] AttributeGroup: Visiting Group AttrGroupType[name=ProcessorProc, ifType=all] for null@1
2014-04-01 11:52:02,394 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,394 DEBUG [Collectd-Thread-2-of-50] AttributeGroup: AttrGroupType[name=ProcessorProc, ifType=all] for null@1.shouldPersist = true
2014-04-01 11:52:02,394 DEBUG [Collectd-Thread-2-of-50] NSClientCollector$NSClientCollectionAttribute: Visiting attribute NSClientCollectionAttribute cpuProcTime=6.2524
2014-04-01 11:52:02,396 DEBUG [Collectd-Thread-2-of-50] OneToOnePersister: Persisting NSClientCollectionAttribute cpuProcTime=6.2524
2014-04-01 11:52:02,396 DEBUG [Collectd-Thread-2-of-50] OneToOnePersister: Storing attribute NSClientCollectionAttribute cpuProcTime=6.2524
2014-04-01 11:52:02,396 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,397 DEBUG [Collectd-Thread-2-of-50] JRobinRrdStrategy: createDefinition: filename /var/lib/opennms/rrd/snmp/1/cpuProcTime.jrb already exists returning null as definition
2014-04-01 11:52:02,397 DEBUG [Collectd-Thread-2-of-50] JRobinRrdStrategy: createRRD: skipping RRD file
2014-04-01 11:52:02,398 INFO [Collectd-Thread-2-of-50] RrdUtils: updateRRD: updating RRD file /var/lib/opennms/rrd/snmp/1/cpuProcTime.jrb with values '1396345922:6.2524'
2014-04-01 11:52:02,398 DEBUG [Collectd-Thread-2-of-50] RrdUtils: updateRRD: RRD update command completed.
2014-04-01 11:52:02,400 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,400 DEBUG [Collectd-Thread-2-of-50] AttributeGroup: Visiting Group AttrGroupType[name=ProcessorPriv, ifType=all] for null@1
2014-04-01 11:52:02,400 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,400 DEBUG [Collectd-Thread-2-of-50] AttributeGroup: AttrGroupType[name=ProcessorPriv, ifType=all] for null@1.shouldPersist = true
2014-04-01 11:52:02,400 DEBUG [Collectd-Thread-2-of-50] NSClientCollector$NSClientCollectionAttribute: Visiting attribute NSClientCollectionAttribute cpuPrivTime=4.68738
2014-04-01 11:52:02,401 DEBUG [Collectd-Thread-2-of-50] OneToOnePersister: Persisting NSClientCollectionAttribute cpuPrivTime=4.68738
2014-04-01 11:52:02,401 DEBUG [Collectd-Thread-2-of-50] OneToOnePersister: Storing attribute NSClientCollectionAttribute cpuPrivTime=4.68738
2014-04-01 11:52:02,401 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,401 DEBUG [Collectd-Thread-2-of-50] JRobinRrdStrategy: createDefinition: filename /var/lib/opennms/rrd/snmp/1/cpuPrivTime.jrb already exists returning null as definition
2014-04-01 11:52:02,401 DEBUG [Collectd-Thread-2-of-50] JRobinRrdStrategy: createRRD: skipping RRD file
2014-04-01 11:52:02,402 INFO [Collectd-Thread-2-of-50] RrdUtils: updateRRD: updating RRD file /var/lib/opennms/rrd/snmp/1/cpuPrivTime.jrb with values '1396345922:4.68738'
2014-04-01 11:52:02,402 DEBUG [Collectd-Thread-2-of-50] RrdUtils: updateRRD: RRD update command completed.
2014-04-01 11:52:02,402 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,402 DEBUG [Collectd-Thread-2-of-50] AttributeGroup: Visiting Group AttrGroupType[name=ProcessorInt, ifType=all] for null@1
2014-04-01 11:52:02,402 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,403 DEBUG [Collectd-Thread-2-of-50] AttributeGroup: AttrGroupType[name=ProcessorInt, ifType=all] for null@1.shouldPersist = true
2014-04-01 11:52:02,403 DEBUG [Collectd-Thread-2-of-50] NSClientCollector$NSClientCollectionAttribute: Visiting attribute NSClientCollectionAttribute cpuIntrTime=0
2014-04-01 11:52:02,403 DEBUG [Collectd-Thread-2-of-50] OneToOnePersister: Persisting NSClientCollectionAttribute cpuIntrTime=0
2014-04-01 11:52:02,403 DEBUG [Collectd-Thread-2-of-50] OneToOnePersister: Storing attribute NSClientCollectionAttribute cpuIntrTime=0
2014-04-01 11:52:02,403 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,403 DEBUG [Collectd-Thread-2-of-50] JRobinRrdStrategy: createDefinition: filename /var/lib/opennms/rrd/snmp/1/cpuIntrTime.jrb already exists returning null as definition
2014-04-01 11:52:02,403 DEBUG [Collectd-Thread-2-of-50] JRobinRrdStrategy: createRRD: skipping RRD file
2014-04-01 11:52:02,403 INFO [Collectd-Thread-2-of-50] RrdUtils: updateRRD: updating RRD file /var/lib/opennms/rrd/snmp/1/cpuIntrTime.jrb with values '1396345922:0'
2014-04-01 11:52:02,404 DEBUG [Collectd-Thread-2-of-50] RrdUtils: updateRRD: RRD update command completed.
2014-04-01 11:52:02,404 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,404 DEBUG [Collectd-Thread-2-of-50] AttributeGroup: Visiting Group AttrGroupType[name=ProcessorUser, ifType=all] for null@1
2014-04-01 11:52:02,404 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,404 DEBUG [Collectd-Thread-2-of-50] AttributeGroup: AttrGroupType[name=ProcessorUser, ifType=all] for null@1.shouldPersist = true
2014-04-01 11:52:02,404 DEBUG [Collectd-Thread-2-of-50] NSClientCollector$NSClientCollectionAttribute: Visiting attribute NSClientCollectionAttribute cpuUserTime=0
2014-04-01 11:52:02,404 DEBUG [Collectd-Thread-2-of-50] OneToOnePersister: Persisting NSClientCollectionAttribute cpuUserTime=0
2014-04-01 11:52:02,404 DEBUG [Collectd-Thread-2-of-50] OneToOnePersister: Storing attribute NSClientCollectionAttribute cpuUserTime=0
2014-04-01 11:52:02,405 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,405 DEBUG [Collectd-Thread-2-of-50] JRobinRrdStrategy: createDefinition: filename /var/lib/opennms/rrd/snmp/1/cpuUserTime.jrb already exists returning null as definition
2014-04-01 11:52:02,405 DEBUG [Collectd-Thread-2-of-50] JRobinRrdStrategy: createRRD: skipping RRD file
2014-04-01 11:52:02,405 INFO [Collectd-Thread-2-of-50] RrdUtils: updateRRD: updating RRD file /var/lib/opennms/rrd/snmp/1/cpuUserTime.jrb with values '1396345922:0'
2014-04-01 11:52:02,405 DEBUG [Collectd-Thread-2-of-50] RrdUtils: updateRRD: RRD update command completed.
2014-04-01 11:52:02,406 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,406 DEBUG [Collectd-Thread-2-of-50] AttributeGroup: Visiting Group AttrGroupType[name=ProcessorProc, ifType=all] for null@1
2014-04-01 11:52:02,406 DEBUG [Collectd-Thread-2-of-50] NSClientCollector$NSClientCollectionAttribute: Visiting attribute NSClientCollectionAttribute cpuProcTime=6.2524
2014-04-01 11:52:02,408 DEBUG [Collectd-Thread-2-of-50] ThresholdingSet: hasThresholds: node@cpuProcTime? true
2014-04-01 11:52:02,408 DEBUG [Collectd-Thread-2-of-50] ThresholdingVisitor: visitAttribute: storing value 6.2524 for attribute named cpuProcTime
2014-04-01 11:52:02,408 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,408 DEBUG [Collectd-Thread-2-of-50] AttributeGroup: Visiting Group AttrGroupType[name=ProcessorPriv, ifType=all] for null@1
2014-04-01 11:52:02,409 DEBUG [Collectd-Thread-2-of-50] NSClientCollector$NSClientCollectionAttribute: Visiting attribute NSClientCollectionAttribute cpuPrivTime=4.68738
2014-04-01 11:52:02,409 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,409 DEBUG [Collectd-Thread-2-of-50] AttributeGroup: Visiting Group AttrGroupType[name=ProcessorInt, ifType=all] for null@1
2014-04-01 11:52:02,409 DEBUG [Collectd-Thread-2-of-50] NSClientCollector$NSClientCollectionAttribute: Visiting attribute NSClientCollectionAttribute cpuIntrTime=0
2014-04-01 11:52:02,409 DEBUG [Collectd-Thread-2-of-50] DefaultCollectionAgent: getStorageDir: isStoreByForeignSource = false, foreignSource = null, foreignId = null, dir = 1
2014-04-01 11:52:02,409 DEBUG [Collectd-Thread-2-of-50] AttributeGroup: Visiting Group AttrGroupType[name=ProcessorUser, ifType=all] for null@1
2014-04-01 11:52:02,409 DEBUG [Collectd-Thread-2-of-50] NSClientCollector$NSClientCollectionAttribute: Visiting attribute NSClientCollectionAttribute cpuUserTime=0
2014-04-01 11:52:02,411 WARN [Collectd-Thread-2-of-50] CollectableService: run: failed collection for 10.10.10.8/NSClientpp/NSClient
2014-04-01 11:52:02,411 ERROR [Collectd-Thread-2-of-50] CollectableService: An undeclared throwable was caught during data collection for interface 10.10.10.8/NSClientpp
org.opennms.netmgt.collectd.CollectionException: An undeclared throwable was caught during data collection for interface 10.10.10.8/NSClientpp
at org.opennms.netmgt.collectd.CollectableService.doCollection(CollectableService.java:396)
at org.opennms.netmgt.collectd.CollectableService.run(CollectableService.java:298)
at org.opennms.netmgt.scheduler.LegacyScheduler$1.run(LegacyScheduler.java:201)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at org.opennms.core.concurrent.LogPreservingThreadFactory$3.run(LogPreservingThreadFactory.java:107)
at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.IllegalArgumentException: CollectionResourceWrapper: Null collection timestamp when thresholding service NSClientpp on node 1 (10.10.10.8)
at org.opennms.netmgt.threshd.CollectionResourceWrapper.<init>(CollectionResourceWrapper.java:129)
at org.opennms.netmgt.threshd.CollectorThresholdingSet.applyThresholds(CollectorThresholdingSet.java:97)
at org.opennms.netmgt.threshd.ThresholdingVisitor.completeResource(ThresholdingVisitor.java:189)
at org.opennms.netmgt.collectd.AbstractCollectionResource.visit(AbstractCollectionResource.java:119)
at org.opennms.protocols.nsclient.collector.NSClientCollector$NSClientCollectionSet.visit(NSClientCollector.java:248)
at org.opennms.netmgt.collectd.CollectableService.doCollection(CollectableService.java:383)
... 6 more
2014-04-01 11:52:02,412 DEBUG [Collectd-Thread-2-of-50] CollectableService: run: change in collection status, generating event.
2014-04-01 11:52:02,420 DEBUG [Collectd-Thread-2-of-50] CollectableService: sendEvent: Sent event uei.opennms.org/nodes/dataCollectionFailed for 1/10.10.10.8/NSClientpp