code: @Override
    public final boolean isValid(final Object pvalue, final ConstraintValidatorContext pcontext) {
      final String valueAsString = Objects.toString(pvalue, null);
  
      if (StringUtils.isEmpty(valueAsString)) {
        // empty field is ok
        return true;
      }
      return allowDin5008 && valueAsString.matches(PHONE_NUMBER_DIN5008) //
          || allowE123 && valueAsString.matches(PHONE_NUMBER_E123) //
          || allowUri && valueAsString.matches(PHONE_NUMBER_URI) //
          || allowMs && valueAsString.matches(PHONE_NUMBER_MS) //
          || allowCommon && valueAsString.matches(PHONE_NUMBER_COMMON);
    }
docs: {@inheritDoc} check if given string is a valid gln.
  
  @see javax.validation.ConstraintValidator#isValid(java.lang.Object,
  javax.validation.ConstraintValidatorContext)