feat: expose whether the client loaded the world for a backend conn

feat(jd): add note for plugins on how to implement timeout behaviour

Author: Timongcraft

api/src/main/java/com/velocitypowered/api/event/player/PlayerClientLoadedWorldEvent.java

@@ -17,6 +17,8 @@
  * <p>This event is fired when the player explicitly notifies the server after loading the world (closing the downloading terrain screen)
  *
  * @implNote Unlike Paper this event will <u>not</u> fire due to a timeout.
+ *     Though plugins can implement a timeout by scheduling a task in {@link ServerPostConnectEvent}
+ *     and checking {@link com.velocitypowered.api.proxy.ServerConnection#isClientLoaded()}.
  * @sinceMinecraft 1.21.4
  * @since 3.4.0
  */

api/src/main/java/com/velocitypowered/api/proxy/ServerConnection.java

@@ -40,6 +40,16 @@ public interface ServerConnection extends ChannelMessageSource, ChannelMessageSi
    */
   ServerInfo getServerInfo();
 
+  /**
+   * Returns whether the client notified this connection of having loaded the world.
+   *
+   * @return true if the client has loaded the world
+   * @implNote This is purely client-dependent; see {@link com.velocitypowered.api.event.player.PlayerClientLoadedWorldEvent}.
+   * @sinceMinecraft 1.21.4
+   * @since 3.4.0
+   */
+  boolean isClientLoaded();
+
   /**
    * Returns the player that this connection is associated with.
    *

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/VelocityServerConnection.java

@@ -68,7 +68,7 @@ public class VelocityServerConnection implements MinecraftConnectionAssociation,
   private final VelocityServer server;
   private @Nullable MinecraftConnection connection;
   private boolean hasCompletedJoin = false;
-  private boolean clientLoaded = false; // 1.21.4+ - does not time out
+  private boolean clientLoaded = false; // 1.21.4+
   private boolean gracefulDisconnect = false;
   private BackendConnectionPhase connectionPhase = BackendConnectionPhases.UNKNOWN;
   private final Map<Long, Long> pendingPings = new HashMap<>();
@@ -323,6 +323,7 @@ public void setClientLoaded(boolean clientLoaded) {
     this.clientLoaded = clientLoaded;
   }
 
+  @Override
   public boolean isClientLoaded() {
     return clientLoaded;
   }