Merge pull request #159 from Devoxin/feature/rest-response-headers

Add Lavalink-Major-Version

Author: freyacodes

IMPLEMENTATION.md

@@ -307,6 +307,8 @@ Additionally, in every `/loadtracks` response, a `loadType` property is returned
 * `NO_MATCHES` - Returned if no matches/sources could be found for a given identifier.
 * `LOAD_FAILED` - Returned if Lavaplayer failed to load something for some reason.
 
+All REST responses from Lavalink include a `Lavalink-Api-Version` header.
+
 ### Special notes
 * When your shard's mainWS connection dies, so does all your lavalink audio connections.
     * This also includes resumes

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

@@ -0,0 +1,21 @@
+package lavalink.server.io;
+
+import org.springframework.stereotype.Component;
+import org.springframework.web.filter.OncePerRequestFilter;
+
+import javax.servlet.FilterChain;
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+
+@Component
+public class ResponseHeaderFilter extends OncePerRequestFilter {
+
+    @Override
+    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
+                                    FilterChain filterChain) throws IOException, ServletException {
+        response.addHeader("Lavalink-Api-Version", "3");
+        filterChain.doFilter(request, response);
+    }
+}