code: public static int findLastIndexOf(Object self, int startIndex, Closure closure) {
          int result = -1;
          int i = 0;
          BooleanClosureWrapper bcw = new BooleanClosureWrapper(closure);
          for (Iterator iter = InvokerHelper.asIterator(self); iter.hasNext(); i++) {
              Object value = iter.next();
              if (i < startIndex) {
                  continue;
              }
              if (bcw.call(value)) {
                  result = i;
              }
          }
          return result;
      }
docs: Iterates over the elements of an iterable collection of items, starting
  from a specified startIndex, and returns the index of the last item that
  matches the condition specified in the closure.
  
  @param self       the iteration object over which to iterate
  @param startIndex start matching from this index
  @param closure    the filter to perform a match on the collection
  @return an integer that is the index of the last matched object or -1 if no match was found
  @since 1.5.2