code: public static <V> FluentFuture<V> from(ListenableFuture<V> future) {
      return future instanceof FluentFuture
          ? (FluentFuture<V>) future
          : new ForwardingFluentFuture<V>(future);
    }
docs: Converts the given {@code ListenableFuture} to an equivalent {@code FluentFuture}.
  
  <p>If the given {@code ListenableFuture} is already a {@code FluentFuture}, it is returned
  directly. If not, it is wrapped in a {@code FluentFuture} that delegates all calls to the
  original {@code ListenableFuture}.