Modify the opening handshake in WebsSocket

In some communication protocol, which is based on WebSocket, we need to read and write the opening handshake header. In Java we can do this with :https://docs.oracle.com/javaee%2F7%2Fapi%2F%2F/javax/websocket/server/ServerEndpointConfig.Configurator.html#modifyHandshake-javax.websocket.server.ServerEndpointConfig-javax.websocket.server.HandshakeRequest-javax.websocket.HandshakeResponse-

public void modifyHandshake(ServerEndpointConfig sec,
                            HandshakeRequest request,
                            HandshakeResponse response)

For example there is a communication protocol, where there is different versions, and the client writes in the header, what versions they are accept. So we need to read it form the header, for example (MyProtocolVersion : 3.4, 4.5 ), and respond (MyProtocolVersion : 3.4) or (MyProtocolVersion : 4.5)

In the future is it possible that we will have access to it?