code: public static String join(Iterable<?> iterable, String separator) {
  		return org.apache.commons.lang3.StringUtils.join(iterable, separator);
  	}
docs: <p>
  Joins the elements of the provided Iterable into a single String
  containing the provided elements.
  </p>
  <p>
  No delimiter is added before or after the list. A null separator is the
  same as an empty String ("").
  </p>
  <p>
  See the examples here: {@link #join(Object[], String)}.
  </p>
  
  @param iterable
  the Iterable providing the values to join together, may be
  null
  @param separator
  the separator character to use, null treated as ""
  @return the joined String, null if null iterator input