In fact here is the javadoc wrong, or in other words: It's by design that the XMPPConnection interface does not declare *any* methods to change the connection state. This is mainly for two reasons:
1. It doesn't need to. XMPPConnection (the interface) is used everywhere in Smack, and nowhere, besides the exception of ReconnectionManager, methods to manipulate the connection state are required.
2. There could be XMPP connection types that are *always connected* (for whatever reason)
Fixed with https://github.com/igniterealtime/Smack/commit/2853ec39b4f38269d97253f4435cda027 43e8bf8