Lavalink Major Version Header (lavalink-devs#111)

* add lavaclient to list of libs which support v3

* testing lavalink version header

* change Lavalink-Version to Lavalink-Major-Version

* update implementation file to make ppl aware of the change

* significant over breaking, removal of non breaking

IMPLEMENTATION.md

@@ -12,10 +12,12 @@ The Java client has support for JDA, but can also be adapted to work with other
     * Hixie 76
     * Hixie 75
 
-## Breaking changes v2.0 -> v3.0 
-The response of `/loadtracks` has been completely changed.
+## Significant changes v2.0 -> v3.0 
+* The response of `/loadtracks` has been completely changed.
+* Lavalink v3.0 now reports its version as a handshake response header.
+`Lavalink-Major-Version` has a value of `3` for v3.0 only. It's missing for any older version.
 
-## Breaking changes v1.3 -> v2.0 
+## Significant changes v1.3 -> v2.0 
 With the release of v2.0 many unnecessary ops were removed:
 
 * `connect`

LavalinkServer/src/main/java/lavalink/server/config/SentryConfiguration.java

@@ -18,7 +18,9 @@
 /**
  * Created by napster on 25.04.18.
  */
+
 @Configuration
+@SuppressWarnings("WeakerAccess")
 public class SentryConfiguration {
 
     private static final Logger log = LoggerFactory.getLogger(SentryConfiguration.class);

LavalinkServer/src/main/java/lavalink/server/io/SocketServer.java

@@ -34,7 +34,10 @@
 import net.dv8tion.jda.Core;
 import net.dv8tion.jda.manager.AudioManager;
 import org.java_websocket.WebSocket;
+import org.java_websocket.drafts.Draft;
+import org.java_websocket.exceptions.InvalidDataException;
 import org.java_websocket.handshake.ClientHandshake;
+import org.java_websocket.handshake.ServerHandshakeBuilder;
 import org.java_websocket.server.WebSocketServer;
 import org.json.JSONObject;
 import org.slf4j.Logger;
@@ -76,6 +79,13 @@ public void start() {
         super.start();
     }
 
+    @Override
+    public ServerHandshakeBuilder onWebsocketHandshakeReceivedAsServer(WebSocket conn, Draft draft, ClientHandshake request) throws InvalidDataException {
+        ServerHandshakeBuilder builder = super.onWebsocketHandshakeReceivedAsServer(conn, draft, request);
+        builder.put("Lavalink-Major-Version", "3");
+        return builder;
+    }
+
     @Override
     public void onOpen(WebSocket webSocket, ClientHandshake clientHandshake) {
         try {