Turn some APIs into no-ops if they apply to clients without the relevant client functionality.

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ConnectedPlayer.java

@@ -330,11 +330,14 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
   public void sendPlayerListHeaderAndFooter(final Component header, final Component footer) {
     this.playerListHeader = Objects.requireNonNull(header, "header");
     this.playerListFooter = Objects.requireNonNull(footer, "footer");
+    if (this.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_8) >= 0) {
       this.connection.write(HeaderAndFooter.create(header, footer, this.getProtocolVersion()));
     }
+  }
 
   @Override
   public void showTitle(net.kyori.adventure.title.@NonNull Title title) {
+    if (this.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_8) >= 0) {
       GsonComponentSerializer serializer = ProtocolUtils.getJsonChatSerializer(this
           .getProtocolVersion());
 
@@ -359,26 +362,35 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
 
       connection.flush();
     }
+  }
 
   @Override
   public void clearTitle() {
+    if (this.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_8) >= 0) {
       connection.write(TitlePacket.hideForProtocolVersion(this.getProtocolVersion()));
     }
+  }
 
   @Override
   public void resetTitle() {
+    if (this.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_8) >= 0) {
       connection.write(TitlePacket.resetForProtocolVersion(this.getProtocolVersion()));
     }
+  }
 
   @Override
   public void hideBossBar(@NonNull BossBar bar) {
+    if (this.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_9) >= 0) {
       this.server.getBossBarManager().removeBossBar(this, bar);
     }
+  }
 
   @Override
   public void showBossBar(@NonNull BossBar bar) {
+    if (this.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_9) >= 0) {
       this.server.getBossBarManager().addBossBar(this, bar);
     }
+  }
 
   @Override
   public ConnectionRequestBuilder createConnectionRequest(RegisteredServer server) {
@@ -835,11 +847,13 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
   public void sendResourcePack(String url) {
     Preconditions.checkNotNull(url, "url");
 
+    if (this.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_8) >= 0) {
       ResourcePackRequest request = new ResourcePackRequest();
       request.setUrl(url);
       request.setHash("");
       connection.write(request);
     }
+  }
 
   @Override
   public void sendResourcePack(String url, byte[] hash) {
@@ -847,11 +861,13 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
     Preconditions.checkNotNull(hash, "hash");
     Preconditions.checkArgument(hash.length == 20, "Hash length is not 20");
 
+    if (this.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_8) >= 0) {
       ResourcePackRequest request = new ResourcePackRequest();
       request.setUrl(url);
       request.setHash(ByteBufUtil.hexDump(hash));
       connection.write(request);
     }
+  }
 
   /**
    * Sends a {@link KeepAlive} packet to the player with a random ID.