Address NPE in getNotScannedBuilds()

From our Jenkins Log:
Caught exception evaluating: it.getBuilds(scanTarget) in /job/job-name/scan-on-demand/. Reason: java.lang.NullPointerException
java.lang.NullPointerException
	at com.sonyericsson.jenkins.plugins.bfa.sod.ScanOnDemandBaseAction.getNotScannedBuilds(ScanOnDemandBaseAction.java:173)
	at com.sonyericsson.jenkins.plugins.bfa.sod.ScanOnDemandBaseAction.getBuilds(ScanOnDemandBaseAction.java:154)
	at com.sonyericsson.jenkins.plugins.bfa.sod.ScanOnDemandBaseAction.getBuilds(ScanOnDemandBaseAction.java:142)
...