Laravel 不验证字段是否为必填字段

我有以下请求验证：

<?php

namespace App\Http\Requests;

use Illuminate\Foundation\Http\FormRequest;

class OwnerEstate extends FormRequest
{
    /**
     * Determine if the user is authorized to make this request.
     *
     * @return bool
     */
    public function authorize()
    {
        return true;
    }

    /**
     * Get the validation rules that apply to the request.
     *
     * @return array
     */
    public function rules()
    {
        return [
            'firstname' => 'required_if:type,individual',
            'secondname'=> 'required_if:type,individual',
            'lastname' => 'required_if:type,individual',
            'pin' => 'required_if:type,individual|digits:10',

            'name' => 'required_if:type,legal-entity',
            'eik' => 'required_if:type,legal-entity|digits:9'
        ];
    }
}

当类型不是单独的时，它仍然检查引脚的“digits：10”验证并返回错误。如果required_if验证不需要该字段，如何禁用其他验证。（我使用的是Laravel 5.5）