code: public static String join(Iterator<?> iterator, CharSequence separator) {
  		return Joiner.on(separator.toString()).useForNull("null").join(toIterable(iterator));
  	}
docs: Returns the concatenated string representation of the elements in the given iterator. The {@code separator} is
  used to between each pair of entries in the input. The string <code>null</code> is used for <code>null</code>
  entries in the input. The given iterator is left exhausted.
  
  @param iterator
  the iterator. May not be <code>null</code>.
  @param separator
  the separator. May not be <code>null</code>.
  @return the string representation of the iterator's elements. Never <code>null</code>.
  @see #join(Iterator, CharSequence, org.eclipse.xtext.xbase.lib.Functions.Function1)