// candidate list (in order). If the system given in the element's
// @system attribute is supported by an available checking engine:
List<XCCDFCheck> supportedChecks = new LinkedList<XCCDFCheck>();
for (XCCDFCheck check : candidateChecks) {
String system = check.getSystem();
CheckSystem checkSystem = CheckSystemRegistry.lookupCheckSystem(system);
if (checkSystem == null) {
if (!unsupportedCheckSystems.contains(checkSystem)) {
log.debug("unsupported check system " + system);
unsupportedCheckSystems.add(system);
}