Class 'GuzzleHttp\Client' not found?

Question

Yii

Good day.
As is clear from the topic, the error Class not found, cms yii2.
Here we turn to the class pastebin.com/U9BDkcLy Line 42
Here is the class itself, which lies in /vendor/guzzlehttp/guzzle/src/Client.php pastebin.com/dvQ0eTuS
Guzzle set via composer :
"require": {
"guzzlehttp/guzzle": "~5.0"
}
Composer.json from /vendor/guzzlehttp pastebin.com/TkA6wtdB
Please tell me what's wrong?