I wrote xmpp server component using Whack. After successfull authentication server sends empty packet and Whack throws exception:
[Component socket reader] ERROR org.jivesoftware.whack.ExternalComponentManager - org.xmlpull.v1.XmlPullParserException: Unknown packet type was read: handshake
But in XEP-0114: Jabber Component Protocol — 3. Protocol Flow pointed:
If the credentials are acceptable, the receiving application (in this case the server) MUST return an empty element.
Thanks for paying attention.
P.S. I'm using tigase v5 server.