Migrate API-only functions out of PlayerDataManager

With the update to 1.16 there's no need to maintain multiple copies of the same code. Additionally, in 1.16 the action bar now supports JSON text.

plugin/src/main/java/com/lishid/openinv/OpenInv.java

@@ -42,6 +42,8 @@ import java.util.Map;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 import java.util.function.Consumer;
+import net.md_5.bungee.api.ChatMessageType;
+import net.md_5.bungee.api.chat.TextComponent;
 import org.bukkit.Bukkit;
 import org.bukkit.OfflinePlayer;
 import org.bukkit.command.Command;
@@ -299,9 +301,21 @@ public class OpenInv extends JavaPlugin implements IOpenInv {
     public void sendSystemMessage(@NotNull Player player, @NotNull String key) {
         String message = this.languageManager.getValue(key, getLocale(player));
 
-        if (message != null) {
-            this.accessor.getPlayerDataManager().sendSystemMessage(player, message);
+        if (message == null) {
+            return;
         }
+
+        int newline = message.indexOf('\n');
+        if (newline != -1) {
+            // No newlines in action bar chat.
+            message = message.substring(0, newline);
+        }
+
+        if (message.isEmpty()) {
+            return;
+        }
+
+        player.spigot().sendMessage(ChatMessageType.ACTION_BAR, TextComponent.fromLegacyText(message));
     }
 
     public @Nullable String getLocalizedMessage(@NotNull CommandSender sender, @NotNull String key) {
@@ -314,7 +328,7 @@ public class OpenInv extends JavaPlugin implements IOpenInv {
 
     private @Nullable String getLocale(@NotNull CommandSender sender) {
         if (sender instanceof Player) {
-            return this.accessor.getPlayerDataManager().getLocale((Player) sender);
+            return ((Player) sender).getLocale();
         } else {
             return this.getConfig().getString("settings.locale", "en_us");
         }