code: public boolean isVersionValid(String version) {
          if (fromVersion != null && version != null) {
              if (version.compareTo(fromVersion) < 0) {
                  return false;
              }
          }
          if (toVersion != null) {
              if (version == null || version.compareTo(toVersion) >= 0) {
                  return false;
              }
          }
          return true;
      }
docs: This method determines if the rule is valid for the
  supplied version. If the supplied version is null, then
  it is assumed to represent 'latest version' and therefore
  any rule with a 'toVersion' set will not be valid.
  
  @param version The version
  @return Whether the rule is valid for the supplied version