@CheckMetadata(id = "employeesAlphaNumeric")
public class MyCustomCheck extends SingleExecutionCheck {

    public MyCustomCheck(String argument, File file) {
        super(argument, file);
    }

    @Override
    public CheckResult performCheck() {
        boolean isMyDocFragmentValid = ... // my custom logic here

        CheckStatus checkStatus;

        if(isMyDocFragmentValid) {
            checkStatus = CheckStatus.GREEN;
        } else {
            checkStatus = CheckStatus.RED;
        }

        return new CheckResult("", LocalDateTime.now(), checkStatus);
    }
}