code: public String normalize(DTDValidatorBase v, char[] cbuf, int start, int end)
      {
          return StringUtil.normalizeSpaces(cbuf, start, end);
      }
docs: Method called when no validation is to be done, but value is still
  to be normalized as much as it can. What this usually means is that
  all regular space (parser earlier on converts other white space to
  spaces, except for specific character entities; and these special
  cases are NOT to be normalized).
  <p>
  The only exception is that CDATA will not do any normalization. But
  for now, let's implement basic functionality that CDTA instance will
  override
  
  @param v Validator that invoked normalization
  
  @return Normalized value as a String, if any changes were done;
  null if input was normalized