code: public void addBlackListedIPv4(final String spec) throws ConfigurationException, FileNotFoundException {
  			if (spec.length() == 0) return; // Skip empty specs
  			if (spec.startsWith("file:")) {
  				final LineIterator lineIterator = new LineIterator(new FastBufferedReader(new InputStreamReader(new FileInputStream(spec.substring(5)), Charsets.ISO_8859_1)));
  				while (lineIterator.hasNext()) {
  					final MutableString line = lineIterator.next();
  					if (line.length() > 0) blackListedIPv4Addresses.add(handleIPv4(line.toString()));
  				}
  			}
  			else blackListedIPv4Addresses.add(handleIPv4(spec));
  	}
docs: Adds a (or a set of) new IPv4 to the black list; the IPv4 can be specified directly or it can be a file (prefixed by
  <code>file:</code>).
  
  @param spec the specification (an IP address, or a file prefixed by <code>file</code>).
  @throws ConfigurationException
  @throws FileNotFoundException