public function requestCommands(): array
    {
        if ($this->_requestCommands === null) {
            $reflection = new ReflectionClass($this);

            $commands = [];
            foreach ($reflection->getConstants() as $name => $value) {
                if (strpos($name, 'RC_') === 0) {
                    $commands[] = $value;
                }
            }

            return $this->_requestCommands = $commands;
        } else {
            return $this->_requestCommands;
        }
    }