code: public static String join(Object[] objects, String separator)
    {
      return objects != null ? join(Arrays.asList(objects), separator) : null;
    }
docs: Join array of objects, converted to string, using specified specified separator. Returns null if given objects
  array is null and empty if empty. If separator is null uses space string instead, like invoking
  {@link Strings#join(Iterable)}. Null objects or empty strings from given <code>objects</code> parameter are
  ignored.
  
  @param objects array of objects to join,
  @param separator string used as separator.
  @return joined string.