code: public static String join(Object[] objects, char separator)
    {
      return join(objects, Character.toString(separator));
    }
docs: Join array of objects, converted to string, using specified separator. Returns null if given objects array is null
  and empty if empty. Null objects or empty strings from given <code>objects</code> parameter are ignored.
  
  @param objects array of objects to join,
  @param separator character used as separator.
  @return joined string.