code: public List<WebhookClient> removeIf(Predicate<WebhookClient> predicate)
      {
          Checks.notNull(predicate, "Predicate");
          List<WebhookClient> clients = new ArrayList<>();
          for (WebhookClient client : webhooks)
          {
              if (predicate.test(client))
                  clients.add(client);
          }
          removeWebhooks(clients);
          return clients;
      }
docs: Removes the specified {@link net.dv8tion.jda.webhook.WebhookClient WebhookClients}
  from this cluster's list of receivers under the conditions of the provided filter.
  <br>The filter should return {@code true} to remove provided clients and {@code false} to retain them.
  
  <p><b>Note that the removed clients are not closed by this operation!</b>
  
  @param  predicate
  The filter
  
  @throws java.lang.IllegalArgumentException
  If the provided filter is {@code null}
  
  @return List of removed clients