Revert "[5.5] Add 'filter by attribute' functionality" (#21909)

* Revert "[5.5] Add assertJsonMissingExact method to TestResponse.php (#21881)"

This reverts commit 2b4aa9f.

* Revert "Add 'filter by attribute' functionality (#21898)"

This reverts commit edc6398.

Author: ntzm

src/Illuminate/Support/Collection.php

@@ -408,15 +408,11 @@ public function except($keys)
     /**
      * Run a filter over each of the items.
      *
-     * @param  mixed|null  $callback
+     * @param  callable|null  $callback
      * @return static
      */
-    public function filter($callback = null)
+    public function filter(callable $callback = null)
     {
-        if (is_string($callback)) {
-            $callback = $this->valueRetriever($callback);
-        }
-
         if ($callback) {
             return new static(Arr::where($this->items, $callback));
         }

tests/Support/SupportCollectionTest.php

@@ -305,13 +305,6 @@ public function testFilter()
         $this->assertEquals(['first' => 'Hello', 'second' => 'World'], $c->filter(function ($item, $key) {
             return $key != 'id';
         })->all());
-
-        $c = new Collection([
-            ['value' => 'foo', 'nested' => ['included' => true]],
-            ['value' => 'bar', 'nested' => ['included' => false]],
-            ['value' => 'baz', 'nested' => ['included' => true]],
-        ]);
-        $this->assertEquals(['foo', 'baz'], $c->filter('nested.included')->pluck('value')->toArray());
     }
 
     public function testHigherOrderKeyBy()