private Concordion createConcordion() {
final String targetDir = outputDir();
if (targetDir == null) {
throw new IllegalStateException("targetDir() cannot be null");
}
final ConcordionBuilder builder =
new ConcordionBuilder() {
}.withTarget(new FileTarget(new File(targetDir))).withCommand(NS_URI, CMD_EXECUTE,
new IsisExecuteCommandWithHeader());
return builder.build();
}