问array_merge删除空字符串

EN

$defaultOptions = [
        'active' => null,
        'activeClass' => 'active',
        'wrapper' => [
            'attributes' => null,
            'templateVars' => null
        ],
        'item' => [
            'hasChildrenClass' => '', // this disappears after array_merge
            'attributes' => null,
            'linkAttrs' => null,
            'templateVars' => null
        ]
    ];

    $options = [
        'active' => [5,3],
        'item' => [
            'attributes' => ['class' => 'test']
        ]
    ];

$options = array_merge($defaultOptions, $options);

[
      'active' => [
        (int) 0 => (int) 5,
        (int) 1 => (int) 3,
      ],
      'activeClass' => 'active',
      'wrapper' => [
        'attributes' => null,
        'templateVars' => null,
      ],
      'item' => [
        'attributes' => [
          'class' => 'test',
        ],
      ],
    ]