code: public static <V, X extends Exception> CheckedFuture<V, X> makeChecked(
        ListenableFuture<V> future, Function<? super Exception, X> mapper) {
      return new MappingCheckedFuture<V, X>(checkNotNull(future), mapper);
    }
docs: Creates a {@link CheckedFuture} out of a normal {@link ListenableFuture}
  and a {@link Function} that maps from {@link Exception} instances into the
  appropriate checked type.
  
  <p>The given mapping function will be applied to an
  {@link InterruptedException}, a {@link CancellationException}, or an
  {@link ExecutionException}.
  See {@link Future#get()} for details on the exceptions thrown.
  
  @since 9.0 (source-compatible since 1.0)