Move bossbar to new legacy package, since it only works on <1.9

The newly created LegacyViaAPI is safe to use, but should hold methods that cannot be universally used on every version

api-legacy/src/main/java/us/myles/ViaVersion/api/Via.java

@@ -78,16 +78,16 @@ public class Via<T> implements ViaAPI<T> {
 
     @Override
     public BossBar createBossBar(String title, BossColor color, BossStyle style) {
-        return new BossBar(com.viaversion.viaversion.api.Via.getAPI().createBossBar(title,
-                com.viaversion.viaversion.api.boss.BossColor.values()[color.ordinal()],
-                com.viaversion.viaversion.api.boss.BossStyle.values()[style.ordinal()]));
+        return new BossBar(com.viaversion.viaversion.api.Via.getAPI().legacyAPI().createLegacyBossBar(title,
+                com.viaversion.viaversion.api.legacy.bossbar.BossColor.values()[color.ordinal()],
+                com.viaversion.viaversion.api.legacy.bossbar.BossStyle.values()[style.ordinal()]));
     }
 
     @Override
     public BossBar createBossBar(String title, float health, BossColor color, BossStyle style) {
-        return new BossBar(com.viaversion.viaversion.api.Via.getAPI().createBossBar(title, health,
-                com.viaversion.viaversion.api.boss.BossColor.values()[color.ordinal()],
-                com.viaversion.viaversion.api.boss.BossStyle.values()[style.ordinal()]));
+        return new BossBar(com.viaversion.viaversion.api.Via.getAPI().legacyAPI().createLegacyBossBar(title, health,
+                com.viaversion.viaversion.api.legacy.bossbar.BossColor.values()[color.ordinal()],
+                com.viaversion.viaversion.api.legacy.bossbar.BossStyle.values()[style.ordinal()]));
     }
 
     @Override

api-legacy/src/main/java/us/myles/ViaVersion/api/boss/BossBar.java

@@ -28,9 +28,9 @@ import java.util.UUID;
 @Deprecated
 public class BossBar<T> {
 
-    private final com.viaversion.viaversion.api.boss.BossBar<T> bossBar;
+    private final com.viaversion.viaversion.api.legacy.bossbar.BossBar bossBar;
 
-    public BossBar(com.viaversion.viaversion.api.boss.BossBar<T> bossBar) {
+    public BossBar(com.viaversion.viaversion.api.legacy.bossbar.BossBar bossBar) {
         this.bossBar = bossBar;
     }
 
@@ -57,7 +57,7 @@ public class BossBar<T> {
     }
 
     public BossBar setColor(BossColor color) {
-        bossBar.setColor(com.viaversion.viaversion.api.boss.BossColor.values()[color.ordinal()]);
+        bossBar.setColor(com.viaversion.viaversion.api.legacy.bossbar.BossColor.values()[color.ordinal()]);
         return this;
     }
 
@@ -66,12 +66,12 @@ public class BossBar<T> {
     }
 
     public BossBar setStyle(BossStyle style) {
-        bossBar.setStyle(com.viaversion.viaversion.api.boss.BossStyle.values()[style.ordinal()]);
+        bossBar.setStyle(com.viaversion.viaversion.api.legacy.bossbar.BossStyle.values()[style.ordinal()]);
         return this;
     }
 
+    @Deprecated
     public BossBar addPlayer(T player) {
-        bossBar.addPlayer(player);
         return this;
     }
 
@@ -82,13 +82,11 @@ public class BossBar<T> {
 
     @Deprecated
     public BossBar addPlayers(T... players) {
-        bossBar.addPlayers(players);
         return this;
     }
 
     @Deprecated
     public BossBar removePlayer(T player) {
-        bossBar.removePlayer(player);
         return this;
     }
 
@@ -98,17 +96,17 @@ public class BossBar<T> {
     }
 
     public BossBar addFlag(BossFlag flag) {
-        bossBar.addFlag(com.viaversion.viaversion.api.boss.BossFlag.values()[flag.ordinal()]);
+        bossBar.addFlag(com.viaversion.viaversion.api.legacy.bossbar.BossFlag.values()[flag.ordinal()]);
         return this;
     }
 
     public BossBar removeFlag(BossFlag flag) {
-        bossBar.removeFlag(com.viaversion.viaversion.api.boss.BossFlag.values()[flag.ordinal()]);
+        bossBar.removeFlag(com.viaversion.viaversion.api.legacy.bossbar.BossFlag.values()[flag.ordinal()]);
         return this;
     }
 
     public boolean hasFlag(BossFlag flag) {
-        return bossBar.hasFlag(com.viaversion.viaversion.api.boss.BossFlag.values()[flag.ordinal()]);
+        return bossBar.hasFlag(com.viaversion.viaversion.api.legacy.bossbar.BossFlag.values()[flag.ordinal()]);
     }
 
     public Set<UUID> getPlayers() {

api/src/main/java/com/viaversion/viaversion/api/ViaAPI.java

@@ -22,10 +22,8 @@
  */
 package com.viaversion.viaversion.api;
 
-import com.viaversion.viaversion.api.boss.BossBar;
-import com.viaversion.viaversion.api.boss.BossColor;
-import com.viaversion.viaversion.api.boss.BossStyle;
 import com.viaversion.viaversion.api.connection.ConnectionManager;
+import com.viaversion.viaversion.api.legacy.LegacyViaAPI;
 import com.viaversion.viaversion.api.platform.ViaPlatform;
 import com.viaversion.viaversion.api.protocol.ProtocolManager;
 import com.viaversion.viaversion.api.protocol.version.ServerProtocolVersion;
@@ -102,27 +100,6 @@ public interface ViaAPI<T> {
      */
     void sendRawPacket(UUID uuid, ByteBuf packet);
 
-    /**
-     * Create a new bossbar instance
-     *
-     * @param title The title
-     * @param color The color
-     * @param style The style
-     * @return BossBar instance
-     */
-    BossBar createBossBar(String title, BossColor color, BossStyle style);
-
-    /**
-     * Create a new bossbar instance
-     *
-     * @param title  The title
-     * @param health Number between 0 and 1
-     * @param color  The color
-     * @param style  The style
-     * @return BossBar instance
-     */
-    BossBar createBossBar(String title, float health, BossColor color, BossStyle style);
-
     /**
      * Returns the supported protocol versions.
      * This method removes any blocked protocol versions.
@@ -138,4 +115,11 @@ public interface ViaAPI<T> {
      * @return a list of protocol versions
      */
     SortedSet<Integer> getFullSupportedVersions();
+
+    /**
+     * Returns legacy api only applicable on/to legacy versions.
+     *
+     * @return legacy api only applicable on/to legacy versions
+     */
+    LegacyViaAPI<T> legacyAPI();
 }

api/src/main/java/com/viaversion/viaversion/api/legacy/LegacyViaAPI.java

@@ -0,0 +1,58 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2021 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.legacy;
+
+import com.viaversion.viaversion.api.legacy.bossbar.BossBar;
+import com.viaversion.viaversion.api.legacy.bossbar.BossColor;
+import com.viaversion.viaversion.api.legacy.bossbar.BossStyle;
+
+/**
+ * API only applicable on or to legacy versions of Minecraft.
+ *
+ * @param <T> player type
+ */
+public interface LegacyViaAPI<T> {
+
+    /**
+     * Creates a new bossbar instance. This only works on pre 1.9 servers for 1.9+ clients.
+     *
+     * @param title  title
+     * @param health health, between 0 and 1 (inclusive)
+     * @param color  color
+     * @param style  style
+     * @return new bossbar instance
+     */
+    BossBar createLegacyBossBar(String title, float health, BossColor color, BossStyle style);
+
+    /**
+     * Creates a new bossbar instance with full health. This only works on pre 1.9 servers for 1.9+ clients.
+     *
+     * @param title title
+     * @param color color
+     * @param style style
+     * @return new bossbar instance
+     */
+    default BossBar createLegacyBossBar(String title, BossColor color, BossStyle style) {
+        return createLegacyBossBar(title, 1F, color, style);
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/legacy/bossbar/BossBar.java

@@ -20,22 +20,21 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package com.viaversion.viaversion.api.boss;
+package com.viaversion.viaversion.api.legacy.bossbar;
 
-import com.viaversion.viaversion.api.Via;
 import com.viaversion.viaversion.api.connection.UserConnection;
 
 import java.util.Set;
 import java.util.UUID;
 
-public abstract class BossBar<T> {
+public interface BossBar {
 
     /**
      * Get the current title
      *
      * @return the title
      */
-    public abstract String getTitle();
+    String getTitle();
 
     /**
      * Change the title
@@ -43,14 +42,14 @@ public abstract class BossBar<T> {
      * @param title Title can be in either JSON or just text
      * @return The BossBar object
      */
-    public abstract BossBar setTitle(String title);
+    BossBar setTitle(String title);
 
     /**
      * Get the health
      *
      * @return float between 0F - 1F
      */
-    public abstract float getHealth();
+    float getHealth();
 
     /**
      * Change the health
@@ -58,14 +57,14 @@ public abstract class BossBar<T> {
      * @param health this float has to be between 0F - 1F
      * @return The BossBar object
      */
-    public abstract BossBar setHealth(float health);
+    BossBar setHealth(float health);
 
     /**
      * Get the bossbar color
      *
      * @return The colour
      */
-    public abstract BossColor getColor();
+    BossColor getColor();
 
     /**
      * Yay colors!
@@ -73,14 +72,14 @@ public abstract class BossBar<T> {
      * @param color Whatever color you want!
      * @return The BossBar object
      */
-    public abstract BossBar setColor(BossColor color);
+    BossBar setColor(BossColor color);
 
     /**
      * Get the bosbar style
      *
      * @return BossStyle
      */
-    public abstract BossStyle getStyle();
+    BossStyle getStyle();
 
     /**
      * Change the bosbar style
@@ -88,19 +87,7 @@ public abstract class BossBar<T> {
      * @param style BossStyle
      * @return The BossBar object
      */
-    public abstract BossBar setStyle(BossStyle style);
-
-    /**
-     * Show the bossbar to a player.
-     *
-     * @param player The player
-     * @return The BossBar object
-     * @deprecated Deprecated use UUID's instead of Player objects {@link #addPlayer(UUID)}
-     */
-    @Deprecated
-    public BossBar addPlayer(T player) {
-        throw new UnsupportedOperationException("This method is not implemented for the platform " + Via.getPlatform().getPlatformName());
-    }
+    BossBar setStyle(BossStyle style);
 
     /**
      * Show the bossbar to a player (uuid). This only works for frontend connections. Use #addConnection(UserConnection) for other types.
@@ -108,7 +95,7 @@ public abstract class BossBar<T> {
      * @param player uuid of the player
      * @return The BossBar object
      */
-    public abstract BossBar addPlayer(UUID player);
+    BossBar addPlayer(UUID player);
 
     /**
      * Show the bossbar to a player connection.
@@ -116,31 +103,7 @@ public abstract class BossBar<T> {
      * @param conn UserConnection of the connection
      * @return The BossBar object
      */
-    public abstract BossBar addConnection(UserConnection conn);
-
-    /**
-     * add multiple players
-     *
-     * @param players list of players
-     * @return The BossBar object
-     * @deprecated Deprecated use UUID's instead of Player objects {@link #addPlayer(UUID)}
-     */
-    @Deprecated
-    public BossBar addPlayers(T... players) {
-        throw new UnsupportedOperationException("This method is not implemented for the platform " + Via.getPlatform().getPlatformName());
-    }
-
-    /**
-     * Remove the bossbar from a player
-     *
-     * @param player The player
-     * @return The BossBar object
-     * @deprecated Deprecated use UUID's instead of Player objects {@link #removePlayer(UUID)}
-     */
-    @Deprecated
-    public BossBar removePlayer(T player) {
-        throw new UnsupportedOperationException("This method is not implemented for the platform " + Via.getPlatform().getPlatformName());
-    }
+    BossBar addConnection(UserConnection conn);
 
     /**
      * Removes the bossbar from a player. This only works for frontend connections. For others types, use #removeConnection(UserConnection)
@@ -148,7 +111,7 @@ public abstract class BossBar<T> {
      * @param uuid The players UUID
      * @return The BossBar object
      */
-    public abstract BossBar removePlayer(UUID uuid);
+    BossBar removePlayer(UUID uuid);
 
     /**
      * Removes the bossbar from a player connection.
@@ -156,7 +119,7 @@ public abstract class BossBar<T> {
      * @param conn The UserConnection
      * @return The BossBar object
      */
-    public abstract BossBar removeConnection(UserConnection conn);
+    BossBar removeConnection(UserConnection conn);
 
     /**
      * Add flags
@@ -164,7 +127,7 @@ public abstract class BossBar<T> {
      * @param flag The flag to add
      * @return The BossBar object
      */
-    public abstract BossBar addFlag(BossFlag flag);
+    BossBar addFlag(BossFlag flag);
 
     /**
      * Remove flags.
@@ -172,53 +135,53 @@ public abstract class BossBar<T> {
      * @param flag The flag to remove
      * @return The BossBar object
      */
-    public abstract BossBar removeFlag(BossFlag flag);
+    BossBar removeFlag(BossFlag flag);
 
     /**
      * @param flag The flag to check against
      * @return True if it has the flag
      */
-    public abstract boolean hasFlag(BossFlag flag);
+    boolean hasFlag(BossFlag flag);
 
     /**
      * Get players. Only returns UUIDs which are front-end. For all connections, use #getConnections()
      *
      * @return UUIDS from players (sorry I lied)
      */
-    public abstract Set<UUID> getPlayers();
+    Set<UUID> getPlayers();
 
     /**
      * Get UserConnections.
      *
      * @return UserConnection from players
      */
-    public abstract Set<UserConnection> getConnections();
+    Set<UserConnection> getConnections();
 
     /**
      * Show the bossbar to everyone (In the getPlayer set)
      *
      * @return The BossBar object
      */
-    public abstract BossBar show();
+    BossBar show();
 
     /**
      * Hide the bossbar from everyone (In the getPlayer set)
      *
      * @return The BossBar object
      */
-    public abstract BossBar hide();
+    BossBar hide();
 
     /**
      * Is it visible?
      *
      * @return visibility changable with show() and hide()
      */
-    public abstract boolean isVisible();
+    boolean isVisible();
 
     /**
      * Get the UUID of this bossbar
      *
      * @return Unique Id for this bossbar
      */
-    public abstract UUID getId();
+    UUID getId();
 }

api/src/main/java/com/viaversion/viaversion/api/legacy/bossbar/BossColor.java

@@ -20,7 +20,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package com.viaversion.viaversion.api.boss;
+package com.viaversion.viaversion.api.legacy.bossbar;
 
 public enum BossColor {
 

api/src/main/java/com/viaversion/viaversion/api/legacy/bossbar/BossFlag.java

@@ -20,7 +20,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package com.viaversion.viaversion.api.boss;
+package com.viaversion.viaversion.api.legacy.bossbar;
 
 public enum BossFlag {
 

api/src/main/java/com/viaversion/viaversion/api/legacy/bossbar/BossStyle.java

@@ -20,7 +20,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package com.viaversion.viaversion.api.boss;
+package com.viaversion.viaversion.api.legacy.bossbar;
 
 public enum BossStyle {
 

bukkit/src/main/java/com/viaversion/viaversion/boss/ViaBossBar.java

@@ -1,49 +0,0 @@
-/*
- * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
- * Copyright (C) 2016-2021 ViaVersion and contributors
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-package com.viaversion.viaversion.boss;
-
-import com.viaversion.viaversion.api.boss.BossBar;
-import com.viaversion.viaversion.api.boss.BossColor;
-import com.viaversion.viaversion.api.boss.BossStyle;
-import org.bukkit.entity.Player;
-
-public class ViaBossBar extends CommonBoss<Player> {
-
-    public ViaBossBar(String title, float health, BossColor color, BossStyle style) {
-        super(title, health, color, style);
-    }
-
-    @Override
-    public BossBar addPlayer(Player player) {
-        addPlayer(player.getUniqueId());
-        return this;
-    }
-
-    @Override
-    public BossBar addPlayers(Player... players) {
-        for (Player p : players)
-            addPlayer(p);
-        return this;
-    }
-
-    @Override
-    public BossBar removePlayer(Player player) {
-        removePlayer(player.getUniqueId());
-        return this;
-    }
-}

bukkit/src/main/java/com/viaversion/viaversion/bukkit/platform/BukkitViaAPI.java

@@ -20,11 +20,7 @@ package com.viaversion.viaversion.bukkit.platform;
 import com.viaversion.viaversion.ViaAPIBase;
 import com.viaversion.viaversion.ViaVersionPlugin;
 import com.viaversion.viaversion.api.Via;
-import com.viaversion.viaversion.api.boss.BossBar;
-import com.viaversion.viaversion.api.boss.BossColor;
-import com.viaversion.viaversion.api.boss.BossStyle;
 import com.viaversion.viaversion.api.connection.UserConnection;
-import com.viaversion.viaversion.boss.ViaBossBar;
 import com.viaversion.viaversion.bukkit.util.ProtocolSupportUtil;
 import io.netty.buffer.ByteBuf;
 import org.bukkit.Bukkit;
@@ -62,16 +58,6 @@ public class BukkitViaAPI extends ViaAPIBase<Player> {
         sendRawPacket(player.getUniqueId(), packet);
     }
 
-    @Override
-    public BossBar<Player> createBossBar(String title, BossColor color, BossStyle style) {
-        return new ViaBossBar(title, 1F, color, style);
-    }
-
-    @Override
-    public BossBar<Player> createBossBar(String title, float health, BossColor color, BossStyle style) {
-        return new ViaBossBar(title, health, color, style);
-    }
-
     /**
      * Returns if this version is a compatibility build for spigot.
      * Eg. 1.9.1 / 1.9.2 allow certain versions to connect

bungee/src/main/java/com/viaversion/viaversion/bungee/platform/BungeeBossBar.java

@@ -1,51 +0,0 @@
-/*
- * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
- * Copyright (C) 2016-2021 ViaVersion and contributors
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-package com.viaversion.viaversion.bungee.platform;
-
-import com.viaversion.viaversion.api.boss.BossBar;
-import com.viaversion.viaversion.api.boss.BossColor;
-import com.viaversion.viaversion.api.boss.BossStyle;
-import com.viaversion.viaversion.boss.CommonBoss;
-import net.md_5.bungee.api.connection.ProxiedPlayer;
-
-public class BungeeBossBar extends CommonBoss<ProxiedPlayer> {
-
-    public BungeeBossBar(String title, float health, BossColor color, BossStyle style) {
-        super(title, health, color, style);
-    }
-
-
-    @Override
-    public BossBar addPlayer(ProxiedPlayer player) {
-        addPlayer(player.getUniqueId());
-        return this;
-    }
-
-    @Override
-    public BossBar addPlayers(ProxiedPlayer... players) {
-        for (ProxiedPlayer p : players)
-            addPlayer(p);
-        return this;
-    }
-
-    @Override
-    public BossBar removePlayer(ProxiedPlayer player) {
-        removePlayer(player.getUniqueId());
-        return this;
-    }
-}

bungee/src/main/java/com/viaversion/viaversion/bungee/platform/BungeeViaAPI.java

@@ -18,9 +18,6 @@
 package com.viaversion.viaversion.bungee.platform;
 
 import com.viaversion.viaversion.ViaAPIBase;
-import com.viaversion.viaversion.api.boss.BossBar;
-import com.viaversion.viaversion.api.boss.BossColor;
-import com.viaversion.viaversion.api.boss.BossStyle;
 import com.viaversion.viaversion.bungee.service.ProtocolDetectorService;
 import io.netty.buffer.ByteBuf;
 import net.md_5.bungee.api.config.ServerInfo;
@@ -38,16 +35,6 @@ public class BungeeViaAPI extends ViaAPIBase<ProxiedPlayer> {
         sendRawPacket(player.getUniqueId(), packet);
     }
 
-    @Override
-    public BossBar createBossBar(String title, BossColor color, BossStyle style) {
-        return new BungeeBossBar(title, 1F, color, style);
-    }
-
-    @Override
-    public BossBar createBossBar(String title, float health, BossColor color, BossStyle style) {
-        return new BungeeBossBar(title, health, color, style);
-    }
-
     /**
      * Forces ViaVersion to probe a server
      *

common/src/main/java/com/viaversion/viaversion/ViaAPIBase.java

@@ -20,7 +20,9 @@ package com.viaversion.viaversion;
 import com.viaversion.viaversion.api.Via;
 import com.viaversion.viaversion.api.ViaAPI;
 import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.legacy.LegacyViaAPI;
 import com.viaversion.viaversion.api.protocol.version.ServerProtocolVersion;
+import com.viaversion.viaversion.legacy.LegacyAPI;
 import io.netty.buffer.ByteBuf;
 
 import java.util.SortedSet;
@@ -29,6 +31,8 @@ import java.util.UUID;
 
 public abstract class ViaAPIBase<T> implements ViaAPI<T> {
 
+    private final LegacyAPI<T> legacy = new LegacyAPI<>();
+
     @Override
     public ServerProtocolVersion getServerVersion() {
         return Via.getManager().getProtocolManager().getServerProtocolVersion();
@@ -71,4 +75,9 @@ public abstract class ViaAPIBase<T> implements ViaAPI<T> {
     public SortedSet<Integer> getFullSupportedVersions() {
         return Via.getManager().getProtocolManager().getSupportedVersions();
     }
+
+    @Override
+    public LegacyViaAPI<T> legacyAPI() {
+        return legacy;
+    }
 }

common/src/main/java/com/viaversion/viaversion/legacy/LegacyAPI.java

@@ -0,0 +1,15 @@
+package com.viaversion.viaversion.legacy;
+
+import com.viaversion.viaversion.api.legacy.LegacyViaAPI;
+import com.viaversion.viaversion.api.legacy.bossbar.BossBar;
+import com.viaversion.viaversion.api.legacy.bossbar.BossColor;
+import com.viaversion.viaversion.api.legacy.bossbar.BossStyle;
+import com.viaversion.viaversion.legacy.bossbar.CommonBoss;
+
+public final class LegacyAPI<T> implements LegacyViaAPI<T> {
+
+    @Override
+    public BossBar createLegacyBossBar(String title, float health, BossColor color, BossStyle style) {
+        return new CommonBoss(title, health, color, style);
+    }
+}

common/src/main/java/com/viaversion/viaversion/legacy/bossbar/CommonBoss.java

@@ -15,17 +15,18 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-package com.viaversion.viaversion.boss;
+package com.viaversion.viaversion.legacy.bossbar;
 
 import com.google.common.base.Preconditions;
 import com.viaversion.viaversion.api.Via;
-import com.viaversion.viaversion.api.boss.BossBar;
-import com.viaversion.viaversion.api.boss.BossColor;
-import com.viaversion.viaversion.api.boss.BossFlag;
-import com.viaversion.viaversion.api.boss.BossStyle;
 import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.legacy.bossbar.BossBar;
+import com.viaversion.viaversion.api.legacy.bossbar.BossColor;
+import com.viaversion.viaversion.api.legacy.bossbar.BossFlag;
+import com.viaversion.viaversion.api.legacy.bossbar.BossStyle;
 import com.viaversion.viaversion.api.protocol.packet.PacketWrapper;
 import com.viaversion.viaversion.api.type.Type;
+import com.viaversion.viaversion.protocols.protocol1_9to1_8.ClientboundPackets1_9;
 import com.viaversion.viaversion.protocols.protocol1_9to1_8.Protocol1_9To1_8;
 
 import java.util.ArrayList;
@@ -37,7 +38,7 @@ import java.util.UUID;
 import java.util.WeakHashMap;
 import java.util.stream.Collectors;
 
-public abstract class CommonBoss<T> extends BossBar<T> {
+public class CommonBoss implements BossBar {
     private final UUID uuid;
     private final Set<UserConnection> connections;
     private final Set<BossFlag> flags;
@@ -127,8 +128,9 @@ public abstract class CommonBoss<T> extends BossBar<T> {
     @Override
     public BossBar addFlag(BossFlag flag) {
         Preconditions.checkNotNull(flag);
-        if (!hasFlag(flag))
+        if (!hasFlag(flag)) {
             flags.add(flag);
+        }
         sendPacket(CommonBoss.UpdateAction.UPDATE_FLAGS);
         return this;
     }
@@ -136,8 +138,9 @@ public abstract class CommonBoss<T> extends BossBar<T> {
     @Override
     public BossBar removeFlag(BossFlag flag) {
         Preconditions.checkNotNull(flag);
-        if (hasFlag(flag))
+        if (hasFlag(flag)) {
             flags.remove(flag);
+        }
         sendPacket(CommonBoss.UpdateAction.UPDATE_FLAGS);
         return this;
     }
@@ -232,7 +235,7 @@ public abstract class CommonBoss<T> extends BossBar<T> {
 
     private PacketWrapper getPacket(UpdateAction action, UserConnection connection) {
         try {
-            PacketWrapper wrapper = PacketWrapper.create(0x0C, null, connection); // TODO don't use fixed packet ids for future support
+            PacketWrapper wrapper = PacketWrapper.create(ClientboundPackets1_9.BOSSBAR, null, connection);
             wrapper.write(Type.UUID, uuid);
             wrapper.write(Type.VAR_INT, action.getId());
             switch (action) {
@@ -269,8 +272,9 @@ public abstract class CommonBoss<T> extends BossBar<T> {
 
     private int flagToBytes() {
         int bitmask = 0;
-        for (BossFlag flag : flags)
+        for (BossFlag flag : flags) {
             bitmask |= flag.getId();
+        }
         return bitmask;
     }
 

common/src/main/java/com/viaversion/viaversion/protocols/protocol1_9to1_8/storage/EntityTracker1_9.java

@@ -20,9 +20,9 @@ package com.viaversion.viaversion.protocols.protocol1_9to1_8.storage;
 import com.google.common.cache.CacheBuilder;
 import com.google.common.collect.Sets;
 import com.viaversion.viaversion.api.Via;
-import com.viaversion.viaversion.api.boss.BossBar;
-import com.viaversion.viaversion.api.boss.BossColor;
-import com.viaversion.viaversion.api.boss.BossStyle;
+import com.viaversion.viaversion.api.legacy.bossbar.BossBar;
+import com.viaversion.viaversion.api.legacy.bossbar.BossColor;
+import com.viaversion.viaversion.api.legacy.bossbar.BossStyle;
 import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.Position;
 import com.viaversion.viaversion.api.minecraft.entities.Entity1_10Types.EntityType;
@@ -254,7 +254,7 @@ public class EntityTracker1_9 extends EntityTracker {
                         String title = (String) metadata.getValue();
                         title = title.isEmpty() ? (type == EntityType.ENDER_DRAGON ? "Ender Dragon" : "Wither") : title;
                         if (bar == null) {
-                            bar = Via.getAPI().createBossBar(title, BossColor.PINK, BossStyle.SOLID);
+                            bar = Via.getAPI().legacyAPI().createLegacyBossBar(title, BossColor.PINK, BossStyle.SOLID);
                             bossBarMap.put(entityId, bar);
                             bar.addConnection(getUser());
                             bar.show();
@@ -271,7 +271,7 @@ public class EntityTracker1_9 extends EntityTracker {
                         float health = Math.max(0.0f, Math.min(((float) metadata.getValue()) / maxHealth, 1.0f));
                         if (bar == null) {
                             String title = type == EntityType.ENDER_DRAGON ? "Ender Dragon" : "Wither";
-                            bar = Via.getAPI().createBossBar(title, health, BossColor.PINK, BossStyle.SOLID);
+                            bar = Via.getAPI().legacyAPI().createLegacyBossBar(title, health, BossColor.PINK, BossStyle.SOLID);
                             bossBarMap.put(entityId, bar);
                             bar.addConnection(getUser());
                             bar.show();

sponge/src/main/java/com/viaversion/viaversion/sponge/platform/SpongeBossBar.java

@@ -1,50 +0,0 @@
-/*
- * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
- * Copyright (C) 2016-2021 ViaVersion and contributors
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-package com.viaversion.viaversion.sponge.platform;
-
-import com.viaversion.viaversion.api.boss.BossBar;
-import com.viaversion.viaversion.api.boss.BossColor;
-import com.viaversion.viaversion.api.boss.BossStyle;
-import com.viaversion.viaversion.boss.CommonBoss;
-import org.spongepowered.api.entity.living.player.Player;
-
-public class SpongeBossBar extends CommonBoss<Player> {
-
-    public SpongeBossBar(String title, float health, BossColor color, BossStyle style) {
-        super(title, health, color, style);
-    }
-
-    @Override
-    public BossBar addPlayer(Player player) {
-        addPlayer(player.getUniqueId());
-        return this;
-    }
-
-    @Override
-    public BossBar addPlayers(Player... players) {
-        for (Player p : players)
-            addPlayer(p);
-        return this;
-    }
-
-    @Override
-    public BossBar removePlayer(Player player) {
-        removePlayer(player.getUniqueId());
-        return this;
-    }
-}

sponge/src/main/java/com/viaversion/viaversion/sponge/platform/SpongeViaAPI.java

@@ -18,9 +18,6 @@
 package com.viaversion.viaversion.sponge.platform;
 
 import com.viaversion.viaversion.ViaAPIBase;
-import com.viaversion.viaversion.api.boss.BossBar;
-import com.viaversion.viaversion.api.boss.BossColor;
-import com.viaversion.viaversion.api.boss.BossStyle;
 import io.netty.buffer.ByteBuf;
 import org.spongepowered.api.entity.living.player.Player;
 
@@ -35,14 +32,4 @@ public class SpongeViaAPI extends ViaAPIBase<Player> {
     public void sendRawPacket(Player player, ByteBuf packet) throws IllegalArgumentException {
         sendRawPacket(player.getUniqueId(), packet);
     }
-
-    @Override
-    public BossBar createBossBar(String title, BossColor color, BossStyle style) {
-        return new SpongeBossBar(title, 1F, color, style);
-    }
-
-    @Override
-    public BossBar createBossBar(String title, float health, BossColor color, BossStyle style) {
-        return new SpongeBossBar(title, health, color, style);
-    }
 }

velocity/src/main/java/com/viaversion/viaversion/velocity/platform/VelocityBossBar.java

@@ -1,29 +0,0 @@
-/*
- * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
- * Copyright (C) 2016-2021 ViaVersion and contributors
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-package com.viaversion.viaversion.velocity.platform;
-
-import com.velocitypowered.api.proxy.Player;
-import com.viaversion.viaversion.api.boss.BossColor;
-import com.viaversion.viaversion.api.boss.BossStyle;
-import com.viaversion.viaversion.boss.CommonBoss;
-
-public class VelocityBossBar extends CommonBoss<Player> {
-    public VelocityBossBar(String title, float health, BossColor color, BossStyle style) {
-        super(title, health, color, style);
-    }
-}

velocity/src/main/java/com/viaversion/viaversion/velocity/platform/VelocityViaAPI.java

@@ -19,9 +19,6 @@ package com.viaversion.viaversion.velocity.platform;
 
 import com.velocitypowered.api.proxy.Player;
 import com.viaversion.viaversion.ViaAPIBase;
-import com.viaversion.viaversion.api.boss.BossBar;
-import com.viaversion.viaversion.api.boss.BossColor;
-import com.viaversion.viaversion.api.boss.BossStyle;
 import io.netty.buffer.ByteBuf;
 
 public class VelocityViaAPI extends ViaAPIBase<Player> {
@@ -35,14 +32,4 @@ public class VelocityViaAPI extends ViaAPIBase<Player> {
     public void sendRawPacket(Player player, ByteBuf packet) throws IllegalArgumentException {
         sendRawPacket(player.getUniqueId(), packet);
     }
-
-    @Override
-    public BossBar createBossBar(String title, BossColor color, BossStyle style) {
-        return new VelocityBossBar(title, 1F, color, style);
-    }
-
-    @Override
-    public BossBar createBossBar(String title, float health, BossColor color, BossStyle style) {
-        return new VelocityBossBar(title, health, color, style);
-    }
 }