code: public RetryerBuilder<V> withRetryListener(@Nonnull RetryListener listener) {
          Preconditions.checkNotNull(listener, "listener may not be null");
          listeners.add(listener);
          return this;
      }
docs: Adds a listener that will be notified of each attempt that is made
  
  @param listener Listener to add
  @return <code>this</code>