code: public String generate(final int[] nodeSizes, final int bad) {
  		buf.setLength(0);
  		for (int i = 0; i < nodes.size() && i < nodeSizes.length; i++) {
  			buf.append(nodes.get(i).getCharacters(nodeSizes[i], bad));
  		}
  		String value = buf.toString();
  		buf.setLength(0);
  		return value;
  	}
docs: Generates a string containing subject to the parameter value only allowed or one half of
  forbidden characters.
  
  @param nodeSizes
  Array with the desire string lengths. For every node there must be only one length
  @param bad
  if 0, only good characters are generated, if 1, 1 - (all - 1) characters are
  generated false, if 2 all characters are generated false.
  @return a string