Add Nullable If validator in laravel 5.4

AppServiceProvider.php

<?php
...
    
class AppServiceProvider extends ServiceProvider
{
    /**
     * Bootstrap any application services.
     *
     * @return void
     */
    public function boot()
    {
      
        $this->app['validator']->resolver(function($translator, $data, $rules, $messages)
        {
            return new CustomValidator($translator, $data, $rules, $messages);
        });
...

CustomValidator.php

<?php
...
    
use Illuminate\Support\Arr;
use Illuminate\Validation\Validator;

class CustomValidator extends Validator
{



    /**
     * Validate that an attribute exists when another attribute has a given value.
     *
     * @param  string  $attribute
     * @param  mixed   $value
     * @param  mixed   $parameters
     * @return bool
     */
    protected function validateNullableIf($attribute, $value, $parameters)
    {
        $this->requireParameterCount(2, $parameters, 'nullable_if');

        $data = Arr::get($this->data, $parameters[0]);

        $values = array_slice($parameters, 1);

        if (is_bool($data)) {
            array_walk($values, function (&$value) {
                if ($value === 'true') {
                    $value = true;
                } elseif ($value === 'false') {
                    $value = false;
                }
            });
        }

        if (in_array($data, $values)) {
            // hit
            $this->rules[$attribute][] = 'nullable';
            return true;
        }
        //miss

        return true;
    }

}

Would you please explain how I can use it with required_if and required_without?