code: public static <T> ThriftCompletableFuture<T> successfulCompletedFuture(T value) {
          final ThriftCompletableFuture<T> future = new ThriftCompletableFuture<>();
          future.onComplete(value);
          return future;
      }
docs: Returns a new {@link ThriftCompletableFuture} instance that has its value set immediately.