Fix conflicts in CollectionInterface

src/Discord/Helpers/Collection.php

@@ -19,5 +19,26 @@
  */
 class Collection implements CollectionInterface
 {
+    /**
+     * The collection discriminator.
+     *
+     * @var ?string
+     */
+    protected $discrim;
+
+    /**
+     * The items contained in the collection.
+     *
+     * @var array
+     */
+    protected $items;
+
+    /**
+     * Class type allowed into the collection.
+     *
+     * @var string
+     */
+    protected $class;
+
     use CollectionTrait;
 }

src/Discord/Helpers/CollectionInterface.php

@@ -22,19 +22,19 @@ interface CollectionInterface extends ArrayAccess, JsonSerializable, IteratorAgg
     public function get(string $discrim, $key);
     public function set($offset, $value);
     public function pull($key, $default = null);
-    public function fill(array $items): static;
-    public function push(...$items): static;
-    public function pushItem($item): static;
+    public function fill(array $items);
+    public function push(...$items);
+    public function pushItem($item);
     public function count(): int;
     public function first();
     public function last();
     public function isset($offset): bool;
     public function has(...$keys): bool;
-    public function filter(callable $callback): static;
+    public function filter(callable $callback);
     public function find(callable $callback);
     public function clear(): void;
-    public function map(callable $callback): static;
-    public function merge($collection): static;
+    public function map(callable $callback);
+    public function merge($collection);
     public function toArray();
     public function offsetExists($offset): bool;
     #[\ReturnTypeWillChange]

src/Discord/Helpers/CollectionTrait.php

@@ -13,27 +13,6 @@
 
 trait CollectionTrait
 {
-    /**
-     * The collection discriminator.
-     *
-     * @var ?string
-     */
-    protected $discrim;
-
-    /**
-     * The items contained in the collection.
-     *
-     * @var array
-     */
-    protected $items;
-
-    /**
-     * Class type allowed into the collection.
-     *
-     * @var string
-     */
-    protected $class;
-
     /**
      * Create a new static.
      *
@@ -353,6 +332,18 @@ public function toArray()
         return $this->items;
     }
 
+    /**
+     * @since 11.0.0
+     *
+     * Get the keys of the items.
+     *
+     * @return int[]|string[]
+     */
+    public function keys(): array
+    {
+        return array_keys($this->items);
+    }
+
     /**
      * If the collection has an offset.
      *