NPE with empty "Property Files"

We've left the Preferences->Ivy->Settings->Property files empty, is this field mandatory?

Error
Fri Nov 05 09:27:35 CET 2010
Unexpected error [java.lang.NullPointerException]: null

java.lang.NullPointerException
at org.apache.ivyde.eclipse.cpcontainer.IvySettingsSetup.getResolvedPropertyFiles(IvySettingsSetup.java:95)
at org.apache.ivyde.eclipse.cpcontainer.IvyClasspathContainerConfiguration.getInheritedPropertyFiles(IvyClasspathContainerConfiguration.java:229)
at org.apache.ivyde.eclipse.cpcontainer.IvyClasspathContainerState.createIvySettings(IvyClasspathContainerState.java:269)
at org.apache.ivyde.eclipse.cpcontainer.IvyClasspathContainerState.getIvy(IvyClasspathContainerState.java:224)
at org.apache.ivyde.eclipse.cpcontainer.IvyClasspathContainerState.doGetIvy(IvyClasspathContainerState.java:185)
at org.apache.ivyde.eclipse.cpcontainer.IvyClasspathContainerState.getIvy(IvyClasspathContainerState.java:136)
at org.apache.ivyde.eclipse.cpcontainer.IvyResolveJob.run(IvyResolveJob.java:69)
at org.apache.ivyde.eclipse.cpcontainer.IvyClasspathContainer.launchResolve(IvyClasspathContainer.java:161)
at org.apache.ivyde.eclipse.cpcontainer.IvyMultiResolveJob.run(IvyMultiResolveJob.java:58)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)