code: public static String format( Collection<String> items, String separator ) {
  
  		StringBuilder sb = new StringBuilder();
  		for( Iterator<String> it = items.iterator(); it.hasNext(); ) {
  			sb.append( it.next());
  			if( it.hasNext())
  				sb.append( separator );
  		}
  
  		return sb.toString();
  	}
docs: Formats a collection of elements as a string.
  @param items a non-null list of items
  @param separator a string to separate items
  @return a non-null string