code: public List<RequestFuture<?>> broadcast(File file)
      {
          Checks.notNull(file, "File");
          return broadcast(file, file.getName());
      }
docs: Sends the provided {@link java.io.File File}
  to all registered {@link net.dv8tion.jda.webhook.WebhookClient WebhookClients}.
  <br>Use {@link WebhookMessage#files(String, Object, Object...)} to send up to 10 files!
  
  <p><b>The provided data should not exceed 8MB in size!</b>
  
  @param  file
  The file that should be sent to the clients
  
  @throws java.lang.IllegalArgumentException
  If the provided file is {@code null}, does not exist or ist not readable
  @throws java.util.concurrent.RejectedExecutionException
  If any of the receivers has been shutdown
  
  @return A list of {@link java.util.concurrent.Future Future} instances
  representing all message tasks.