Websocket gets closed immediately

The connection is established and remains open now, whoohoo!

Although some other problems arose...

If I call e.g. ws.send( JSON.stringify( { "type":'discoveryResponse', "data":[] } ) );, then the connection gets closed, and the server logs the following:

14:47:53.714 [vert.x-eventloop-thread-0] INFO com.my.GatewayWSVerticle - registered WS for [11.111.111.111]
14:48:26.090 [vert.x-eventloop-thread-0] ERROR i.vertx.core.net.impl.ConnectionBase - io.netty.handler.codec.CorruptedFrameException: unmasked client to server frame
14:48:26.090 [vert.x-eventloop-thread-0] INFO com.my.GatewayWSVerticle - unregistered WS for [11.111.111.111]

If I call ws.initializeConnection(); then I get to see the following in the logs:

14:50:14.331 [vert.x-eventloop-thread-0] ERROR i.vertx.core.net.impl.ConnectionBase - io.netty.handler.codec.CorruptedFrameException: unmasked client to server frame
14:50:14.331 [vert.x-eventloop-thread-0] ERROR i.vertx.core.net.impl.ConnectionBase - io.netty.handler.codec.DecoderException: io.netty.util.IllegalReferenceCountException: refCnt: 0