code: public void setRawComment(String key, String rawComment) {
  	if (rawComment == null)
  	    throw new NullPointerException();
          Entry entry = props.get(key);
          if (entry == null) {
              entry = new Entry(rawComment, null);
              props.put(key, entry);
          } else {
              entry.setRawComment(rawComment);
          }
      }
docs: Sets the "raw" comment for the specified key.  Each line of the
  comment must be either empty, whitespace-only, or preceded by a
  comment marker ("#" or "!").  This is not enforced by this class.
  <br>
  Note: if you set a comment, you must set a corresponding value before
  calling store or storeToXML.
  
  @param key property key whose comment should be set
  @param rawComment raw comment to go with property key, "" for no comment