" title="class or interface in java.lang">IllegalStateException</a></pre>
<div class="block">Register to handle to incoming messages in this conversation. A maximum of one message handler per
 native websocket message type (text, binary, pong) may be added to each Session. I.e. a maximum
 of one message handler to handle incoming text messages a maximum of one message handler for
 handling incoming binary messages, and a maximum of one for handling incoming pong
 messages. For further details of which messa