framework/validators/BooleanValidator.php
protected function validateValue($value)
    {
        if ($this->strict) {
            $valid = $value === $this->trueValue || $value === $this->falseValue;
        } else {
            $valid = $value == $this->trueValue || $value == $this->falseValue;
        }

        if (!$valid) {
            return [$this->message, [
                'true' => $this->trueValue === true ? 'true' : $this->trueValue,
                'false' => $this->falseValue === false ? 'false' : $this->falseValue,
            ]];
        }

        return null;
    }
protected function validateValue($value)
    {
        if ($this->strict) {
            $valid = $value === $this->trueValue || $value === $this->falseValue;
        } else {
            $valid = $value == $this->trueValue || $value == $this->falseValue;
        }

        if (!$valid) {
            return [$this->message, [
                'true' => $this->trueValue === true ? 'true' : $this->trueValue,
                'false' => $this->falseValue === false ? 'false' : $this->falseValue,
            ]];
        }

        return null;
    }
{@inheritdoc}