question: private static int lastIndexOf ( Object o , @ NotNull Object [ ] elements , int index ) { if ( o == null ) { for ( int i = index ; i >= 0 ; i -- ) { if ( elements [ i ] == null ) { return i ; } } } else { for ( int i = index ; i >= 0 ; i -- ) { if ( o . equals ( elements [ i ] ) ) { return i ; } } } return - 1 ; }
target:  static version of lastIndexOf.