code: private String normalize(String str){
  		str = StringUtils.trimToEmpty(str);
  		str = StringUtils.normalizeSpace(str);
  
  		// remove whitespace before punctuation. not using \p{Punct},
  		// because it includes to many special characters.
  		str = str.replaceAll("\\s+(?=[.!,\\?;:])", "");
  
  		return str;
  	}
docs: Normalizes the Strings in the TextPair.
  This mainly deals with whitespace-issues.
  Other normalizations can be included.
  
  @param str
  @return