Added CompleterHelper#empty method

Author: Despical

src/main/java/me/despical/commandframework/CompleterHelper.java

@@ -65,6 +65,21 @@ public List<String> playerNames() {
             .toList();
     }
 
+    /**
+     * Returns an empty, immutable list of strings.
+     * <p>
+     * This method is commonly used to terminate tab completion suggestions,
+     * indicating that no matches or further arguments are available for the
+     * current context.
+     *
+     * @return An empty, immutable list. Never returns null.
+     */
+    @NotNull
+    @Contract(pure = true)
+    public List<String> empty() {
+        return List.of();
+    }
+
     /**
      * Filters a collection of strings based on the argument at the specified index.
      * <p>