code: private <T> CompletableFuture<T> executeOnPooledConnection(
        Address address,
        String type,
        Function<ClientConnection, CompletableFuture<T>> callback,
        Executor executor) {
      CompletableFuture<T> future = new CompletableFuture<T>();
      executeOnPooledConnection(address, type, callback, executor, future);
      return future;
    }
docs: Executes the given callback on a pooled connection.
  
  @param address  the connection address
  @param type     the message type to map to the connection
  @param callback the callback to execute
  @param executor an executor on which to complete the callback future
  @param <T>      the callback response type
  @return a future to be completed once the callback future is complete