Laravel prohibited_if validation rule

ValidationServiceProvider.php

<?php

namespace App\Providers;

use Illuminate\Support\Arr;
use Illuminate\Support\Facades\Validator;
use Illuminate\Support\ServiceProvider;
use Illuminate\Support\Str;

class ValidationServiceProvider extends ServiceProvider
{
    public function boot()
    {
        Validator::extendDependent('prohibited_if', function ($attribute, $value, $parameters, $validator) {
            $validator->requireParameterCount(2, $parameters, 'prohibited_if');

            [$values, $other] = $this->prepareValuesAndOther($parameters, $validator);

            if (in_array($other, $values, true)) {
                return !$validator->validateRequired($attribute, $value);
            }

            return true;
        });

        Validator::replacer('prohibited_if', function ($message, $attribute, $rule, $parameters) {
            return "The {$attribute} field is prohibited when the {$parameters[0]} field is {$parameters[1]}.";
        });
    }

    /** @see \Illuminate\Validation\Concerns\ValidatesAttributes::prepareValuesAndOther() */
    protected function prepareValuesAndOther($parameters, $validator)
    {
        $other = Arr::get($validator->getData(), $parameters[0]);

        $values = array_slice($parameters, 1);

        if (is_bool($other)) {
            $values = $this->convertValuesToBoolean($values);
        } elseif (is_null($other)) {
            $values = $this->convertValuesToNull($values);
        }

        return [$values, $other];
    }

    /** @see \Illuminate\Validation\Concerns\ValidatesAttributes::covertValuesToBoolean() */
    protected function convertValuesToBoolean($values)
    {
        return array_map(function ($value) {
            if ($value === 'true') {
                return true;
            } elseif ($value === 'false') {
                return false;
            }

            return $value;
        }, $values);
    }

    /** @see \Illuminate\Validation\Concerns\ValidatesAttributes::convertValuesToNull() */
    protected function convertValuesToNull($values)
    {
        return array_map(function ($value) {
            return Str::lower($value) === 'null' ? null : $value;
        }, $values);
    }
}