Use return value from add/remove and add abstract isFrontEnd

common/src/main/java/us/myles/ViaVersion/api/platform/ViaConnectionManager.java

@@ -3,7 +3,6 @@ package us.myles.ViaVersion.api.platform;
 import io.netty.channel.ChannelFutureListener;
 import org.jetbrains.annotations.Nullable;
 import us.myles.ViaVersion.api.data.UserConnection;
-import us.myles.ViaVersion.protocols.base.ProtocolInfo;
 
 import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
@@ -17,9 +16,12 @@ public class ViaConnectionManager {
 
     public void onLoginSuccess(UserConnection connection) {
         Objects.requireNonNull(connection, "connection is null!");
-        UUID id = connection.getProtocolInfo().getUuid();
         connections.add(connection);
+
+        if (isFrontEnd(connection)) {
+            UUID id = connection.getProtocolInfo().getUuid();
             clients.put(id, connection);
+        }
 
         if (connection.getChannel() != null) {
             connection.getChannel().closeFuture().addListener((ChannelFutureListener) future -> onDisconnect(connection));
@@ -28,10 +30,21 @@ public class ViaConnectionManager {
 
     public void onDisconnect(UserConnection connection) {
         Objects.requireNonNull(connection, "connection is null!");
-        UUID id = connection.getProtocolInfo().getUuid();
         connections.remove(connection);
+
+        if (isFrontEnd(connection)) {
+            UUID id = connection.getProtocolInfo().getUuid();
             clients.remove(id);
         }
+    }
+
+    /**
+     * Frontend connections will have the UUID stored. Override this if your platform isn't always frontend.
+     * UUIDs can't be duplicate between frontend connections.
+     */
+    protected boolean isFrontEnd(UserConnection conn) {
+        return true;
+    }
 
     /**
      * Returns a map containing the UUIDs and frontend UserConnections from players connected to this proxy server

common/src/main/java/us/myles/ViaVersion/boss/CommonBoss.java

@@ -8,7 +8,6 @@ import us.myles.ViaVersion.api.boss.BossColor;
 import us.myles.ViaVersion.api.boss.BossFlag;
 import us.myles.ViaVersion.api.boss.BossStyle;
 import us.myles.ViaVersion.api.data.UserConnection;
-import us.myles.ViaVersion.api.protocol.ProtocolVersion;
 import us.myles.ViaVersion.api.type.Type;
 import us.myles.ViaVersion.protocols.protocol1_9to1_8.Protocol1_9To1_8;
 
@@ -17,13 +16,13 @@ import java.util.stream.Collectors;
 
 public abstract class CommonBoss<T> extends BossBar<T> {
     private final UUID uuid;
+    private final Set<UserConnection> connections;
+    private final Set<BossFlag> flags;
     private String title;
     private float health;
     private BossColor color;
     private BossStyle style;
-    private final Set<UserConnection> connections;
     private boolean visible;
-    private final Set<BossFlag> flags;
 
     public CommonBoss(String title, float health, BossColor color, BossStyle style) {
         Preconditions.checkNotNull(title, "Title cannot be null");
@@ -83,12 +82,9 @@ public abstract class CommonBoss<T> extends BossBar<T> {
 
     @Override
     public BossBar addConnection(UserConnection conn) {
-        if (!connections.contains(conn)) {
+        if (connections.add(conn) && visible) {
-            connections.add(conn);
-            if (visible) {
             sendPacketConnection(conn, getPacket(CommonBoss.UpdateAction.ADD, conn));
         }
-        }
         return this;
     }
 
@@ -99,8 +95,7 @@ public abstract class CommonBoss<T> extends BossBar<T> {
 
     @Override
     public BossBar removeConnection(UserConnection conn) {
-        if (connections.contains(conn)) {
+        if (connections.remove(conn)) {
-            connections.remove(conn);
             sendPacketConnection(conn, getPacket(UpdateAction.REMOVE, conn));
         }
         return this;
@@ -158,6 +153,13 @@ public abstract class CommonBoss<T> extends BossBar<T> {
         return visible;
     }
 
+    private void setVisible(boolean value) {
+        if (visible != value) {
+            visible = value;
+            sendPacket(value ? CommonBoss.UpdateAction.ADD : CommonBoss.UpdateAction.REMOVE);
+        }
+    }
+
     @Override
     public UUID getId() {
         return uuid;
@@ -186,13 +188,6 @@ public abstract class CommonBoss<T> extends BossBar<T> {
         return flags;
     }
 
-    private void setVisible(boolean value) {
-        if (visible != value) {
-            visible = value;
-            sendPacket(value ? CommonBoss.UpdateAction.ADD : CommonBoss.UpdateAction.REMOVE);
-        }
-    }
-
     private void sendPacket(UpdateAction action) {
         for (UserConnection conn : new ArrayList<>(connections)) {
             PacketWrapper wrapper = getPacket(action, conn);