void setPayloadType(String payloadType) {
        this.payloadType = payloadType;
    }
Sets the type of payload data to be provided at the node. Usually specified by the
namespace of the payload (if any).

@param payloadType the type of payload data to be provided at the node.
xmppserver/src/main/java/org/jivesoftware/openfire/pubsub/Node.java