#3662: Add deprecation warning to ComponentSerializer.toString(Object)

It taking all objects is error-prone, deprecate it and create overloads
for used acceptable types.

chat/src/main/java/net/md_5/bungee/chat/ComponentSerializer.java

@@ -20,6 +20,7 @@
 import net.md_5.bungee.api.chat.SelectorComponent;
 import net.md_5.bungee.api.chat.TextComponent;
 import net.md_5.bungee.api.chat.TranslatableComponent;
+import net.md_5.bungee.api.chat.hover.content.Content;
 import net.md_5.bungee.api.chat.hover.content.Entity;
 import net.md_5.bungee.api.chat.hover.content.EntitySerializer;
 import net.md_5.bungee.api.chat.hover.content.Item;
@@ -158,11 +159,28 @@ public static JsonElement toJson(ComponentStyle style)
         return gson.toJsonTree( style );
     }
 
+    /**
+     * @param object the object to serialize
+     * @return the JSON string representation of the object
+     * @deprecated Error-prone, be careful which object you input here
+     */
+    @Deprecated
     public static String toString(Object object)
     {
         return gson.toJson( object );
     }
 
+    /**
+     * @param content the content to serialize
+     * @return the JSON string representation of the object
+     * @deprecated for legacy internal use only
+     */
+    @Deprecated
+    public static String toString(Content content)
+    {
+        return gson.toJson( content );
+    }
+
     public static String toString(BaseComponent component)
     {
         return gson.toJson( component );