code: public boolean addAll(Collection<? extends T> c, Object identifier) {
          checkNotNullArgument(c);
          if (isPublisherThread()) {
              boolean changed = false;
              if (identifier != null) {
                  final Long id = subscriberIdentifiers.get(identifier);
                  checkNotNullIdentifier(id);
                  changed = queues.get(id).addAll(c);
              } else {
                  for (Queue<T> queue : queues.values()) {
                      if (queue.addAll(c)) {
                          changed = true;
                      }
                  }
              }
              return changed;
          }
          return getCurrentThreadQueue().addAll(c);
      }
docs: Adds a collection of objects to the queue, targeting only the subscriber identified by the provided identifier object, unless said object is null. The added objects will only be visible to the
  subscriber.
  
  @param c The collection of objects to add
  @param identifier The identifier object, can be null
  @return True if this queue changed as a result of the call
  @see #addAll(java.util.Collection)