code: public void validate() {
      if (StringUtils.isEmpty(name) || StringUtils.isEmpty(group)) {
        throw new IllegalArgumentException("Package name or group not set.");
      }
      if (filters.isEmpty()) {
        throw new IllegalArgumentException("No package filter defined / no package root path set.");
      }
      if (created == null) {
        throw new IllegalArgumentException("Package creation date not set.");
      }
    }
docs: Validates that the mandatory properties are set.