Optional NBT payload for custom click events

api/src/main/java/net/kyori/adventure/text/event/ClickEvent.java

@@ -33,6 +33,7 @@
 import net.kyori.adventure.nbt.api.BinaryTagHolder;
 import net.kyori.adventure.text.format.StyleBuilderApplicable;
 import net.kyori.adventure.util.Index;
+import org.jspecify.annotations.Nullable;
 
 import static java.util.Objects.requireNonNull;
 
@@ -179,6 +180,17 @@ static ClickEvent<Payload.Dialog> showDialog(final DialogLike dialog) {
     return ClickEventImpl.create(Action.SHOW_DIALOG, Payload.dialog(dialog));
   }
 
+  /**
+   * Creates a click event that sends a custom event to the server.
+   *
+   * @param key the key identifying the payload
+   * @return the click event
+   * @since 4.23.0
+   */
+  static ClickEvent<Payload.Custom> custom(final Key key) {
+    return ClickEvent.custom(key, null);
+  }
+
   /**
    * Creates a click event that sends a custom event to the server.
    *
@@ -190,9 +202,8 @@ static ClickEvent<Payload.Dialog> showDialog(final DialogLike dialog) {
    * @return the click event
    * @since 4.23.0
    */
-  static ClickEvent<Payload.Custom> custom(final Key key, final BinaryTagHolder nbt) {
+  static ClickEvent<Payload.Custom> custom(final Key key, final @Nullable BinaryTagHolder nbt) {
     requireNonNull(key, "key");
-    requireNonNull(nbt, "nbt");
     return ClickEventImpl.create(Action.CUSTOM, Payload.custom(key, nbt));
   }
 
@@ -464,20 +475,30 @@ static ClickEvent.Payload.Dialog dialog(final DialogLike dialog) {
       return new PayloadImpl.DialogImpl(dialog);
     }
 
+    /**
+     * Creates a custom payload.
+     *
+     * @param key the key identifying the payload
+     * @return the payload
+     * @since 4.23.0
+     */
+    static ClickEvent.Payload.Custom custom(final Key key) {
+      return ClickEvent.Payload.custom(key, null);
+    }
+
     /**
      * Creates a custom payload.
      *
      * <p>See {@link BinaryTagHolder#binaryTagHolder(String)} for a simple way to create NBT from SNBT.
      * For simple use cases, you can use plain strings directly as SNBT.</p>
      *
      * @param key the key identifying the payload
-     * @param nbt the payload nbt data
+     * @param nbt the payload nbt data, optional
      * @return the payload
      * @since 4.23.0
      */
-    static ClickEvent.Payload.Custom custom(final Key key, final BinaryTagHolder nbt) {
+    static ClickEvent.Payload.Custom custom(final Key key, final @Nullable BinaryTagHolder nbt) {
       requireNonNull(key, "key");
-      requireNonNull(nbt, "nbt");
       return new PayloadImpl.CustomImpl(key, nbt);
     }
 
@@ -528,21 +549,21 @@ sealed interface Dialog extends Payload permits PayloadImpl.DialogImpl {
     }
 
     /**
-     * A payload that holds custom data.
+     * A payload with a key and optional custom NBT data.
      *
      * @see Action#CUSTOM
      * @since 4.22.0
      */
     sealed interface Custom extends Payload, Keyed permits PayloadImpl.CustomImpl {
       /**
-       * The custom data.
+       * The optional custom data.
        *
        * <p>See {@link BinaryTagHolder#string()} for a simple way to return SNBT from NBT data.</p>
        *
        * @return the data
        * @since 4.23.0
        */
-      BinaryTagHolder nbt();
+      @Nullable BinaryTagHolder nbt();
     }
   }
 }

api/src/main/java/net/kyori/adventure/text/event/PayloadImpl.java

@@ -26,6 +26,7 @@
 import net.kyori.adventure.dialog.DialogLike;
 import net.kyori.adventure.key.Key;
 import net.kyori.adventure.nbt.api.BinaryTagHolder;
+import org.jspecify.annotations.Nullable;
 
 final class PayloadImpl {
   private PayloadImpl() {
@@ -40,6 +41,6 @@ record IntImpl(int integer) implements ClickEvent.Payload.Int {
   record DialogImpl(DialogLike dialog) implements ClickEvent.Payload.Dialog {
   }
 
-  record CustomImpl(Key key, BinaryTagHolder nbt) implements ClickEvent.Payload.Custom {
+  record CustomImpl(Key key, @Nullable BinaryTagHolder nbt) implements ClickEvent.Payload.Custom {
   }
 }

text-minimessage/src/main/java/net/kyori/adventure/text/minimessage/tag/standard/ClickTag.java

@@ -62,7 +62,10 @@ record ClickTag() {
           }, QuotingOverride.QUOTED);
 
       if (payload instanceof ClickEvent.Payload.Custom custom) {
-        emitter.argument(custom.nbt().string());
+        final BinaryTagHolder nbt = custom.nbt();
+        if (nbt != null) {
+          emitter.argument(nbt.string());
+        }
       }
     })
   );
@@ -90,9 +93,14 @@ static Tag create(final ArgumentQueue args, final Context ctx) throws ParsingExc
           throw ctx.newException("'custom' click event requires a valid key argument", ex, args);
         }
 
-        final String nbt = args.popOr("'custom' click event requires a nbt argument").value();
+        final String nbt;
+        if (args.hasNext()) {
+          nbt = args.pop().value();
+        } else {
+          nbt = null;
+        }
 
-        yield ClickEvent.custom(key, BinaryTagHolder.binaryTagHolder(nbt));
+        yield ClickEvent.custom(key, nbt == null ? null : BinaryTagHolder.binaryTagHolder(nbt));
       }
       case ClickEvent.Action.ShowDialog ignored ->
         throw ctx.newException("'show_dialog' click events are not supported in MiniMessage yet");

text-serializer-gson/src/main/java/net/kyori/adventure/text/serializer/gson/StyleSerializer.java

@@ -227,7 +227,7 @@ public Style read(final JsonReader in) throws IOException {
               if (value != null) style.clickEvent(ClickEvent.copyToClipboard(value));
             }
             case ClickEvent.Action.Custom ignored -> {
-              if (key != null && value != null) style.clickEvent(ClickEvent.custom(key, BinaryTagHolder.binaryTagHolder(value)));
+              if (key != null) style.clickEvent(ClickEvent.custom(key, value == null ? null : BinaryTagHolder.binaryTagHolder(value)));
             }
             // Not readable.
             case ClickEvent.Action.ShowDialog ignored -> {
@@ -360,8 +360,12 @@ private void writeClickEvent(final ClickEvent<?> clickEvent, final JsonWriter ou
         case ClickEvent.Payload.Custom customPayload -> {
           out.name(CLICK_EVENT_ID);
           this.gson.toJson(customPayload.key(), SerializerFactory.KEY_TYPE, out);
-          out.name(CLICK_EVENT_PAYLOAD);
-          out.value(customPayload.nbt().string());
+
+          final BinaryTagHolder nbt = customPayload.nbt();
+          if (nbt != null) {
+            out.name(CLICK_EVENT_PAYLOAD);
+            out.value(nbt.string());
+          }
         }
         case ClickEvent.Payload.Int intPayload -> {
           out.name(CLICK_EVENT_PAGE);