src/FixerNameValidator.php
public function isValid($name, $isCustom)
    {
        if (!$isCustom) {
            return 1 === Preg::match('/^[a-z][a-z0-9_]*$/', $name);
        }

        return 1 === Preg::match('/^[A-Z][a-zA-Z0-9]*\/[a-z][a-z0-9_]*$/', $name);
    }
public function isValid($name, $isCustom)
    {
        if (!$isCustom) {
            return 1 === Preg::match('/^[a-z][a-z0-9_]*$/', $name);
        }

        return 1 === Preg::match('/^[A-Z][a-zA-Z0-9]*\/[a-z][a-z0-9_]*$/', $name);
    }
@param string $name
@param bool   $isCustom

@return bool