title: How to access nested item in Rule::requiredIf() validation
body: <p>I'm trying to validate an array inside a custom Request. The rule evaluates to required if two conditions are met:</p>
  <ol>
  <li>attribute3 is <code>true</code></li>
  <li>another column from the same array is <code>true</code></li>
  </ol>
  <p>Here's what I'm doing:</p>
  <pre><code>public function rules()
  {
      return [
          'attribute1' =&gt; 'required',
          'attribute2' =&gt; 'required',
          'attribute3' =&gt; 'required',
          ...
          'attribute10.*.column3' =&gt; Rule::requiredIf(fn() =&gt; $this-&gt;attribute3), // &lt;- array
          'attribute10.*.column4' =&gt; Rule::requiredIf(fn() =&gt; $this-&gt;attribute3), // &lt;- array
          'attribute10.*.column5' =&gt; Rule::requiredIf(fn() =&gt; $this-&gt;attribute3), // &lt;- array
      ];
  }
  </code></pre>
  <p>What I really need is this:</p>
  <pre><code>'attribute10.*.column4' =&gt; Rule::requiredIf(fn($item &lt;- magically hint this currently looped item) =&gt; $this-&gt;attribute3 &amp;&amp; $item-&gt;column2 &lt;- so I can use it like this), // &lt;- array
  </code></pre>