On hosts where augeas can not access /etc/cron.d for whaterver reason (or any of the other augeas based resources) the log is filled with exceptions like the one below

We should catch those and just log a one liner of with the the message of the IllegalStateException that Augeas was throwing and then return an empty collection instead of letting the Exception bubble up into the plugin container.

2010-05-26 12:33:44,017 WARN  [InventoryManager.discovery-1] (rhq.core.pc.inventory.InventoryManager)- Failure during discovery for [Cron] Resources - failed after 17 ms.
java.lang.Exception: Discovery component invocation failed.
        at org.rhq.core.pc.util.DiscoveryComponentProxyFactory$ComponentInvocationThread.call(DiscoveryComponentProxyFactory.java:270)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
        at java.util.concurrent.FutureTask.run(FutureTask.java:138)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
        at java.lang.Thread.run(Thread.java:637)
Caused by: java.lang.IllegalStateException: Could not list files in /etc/cron.d
        at org.rhq.augeas.util.Glob.match(Glob.java:128)
        at org.rhq.augeas.util.Glob.matchAll(Glob.java:145)
        at org.rhq.plugins.augeas.AugeasConfigurationDiscoveryComponent.checkFiles(AugeasConfigurationDiscoveryComponent.java:130)
        at org.rhq.plugins.augeas.AugeasConfigurationDiscoveryComponent.discoverResources(AugeasConfigurationDiscoveryComponent.java:63)
        at sun.reflect.GeneratedMethodAccessor107.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.rhq.core.pc.util.DiscoveryComponentProxyFactory$ComponentInvocationThread.call(DiscoveryComponentProxyFactory.java:266)
        ... 5 more