Zend\Diactoros\Stream::getContents PHP Method

    public function getContents()
    {
        if (!$this->isReadable()) {
            throw new RuntimeException('Stream is not readable');
        }
        $result = stream_get_contents($this->resource);
        if (false === $result) {
            throw new RuntimeException('Error reading from stream');
        }
        return $result;
    }