1. org.jivesoftware.smackx.pubsub.GetItemsRequest constructor GetItemsRequest(String nodeId, String subscriptionId, int maxItems) the local variable maxItems is never set to the argument maxItems.
2. in toXml, in the block if (getSubscriptionId() != null) the xml should not be ended - builder.append("'/>"); should be builder.append("' ");
3. in toXml, in the block if (getMaxItems() > 0) the xml should not be ended - builder.append("'/>"); should be builder.append("' ");