`ServerRequestFactory` created request with incorrect parsed body

[vjik]

Parsed body always null, but by PSR-7 in certain cases, it must contain certain values:

If the request Content-Type is either application/x-www-form-urlencoded
or multipart/form-data, and the request method is POST, this method MUST
return the contents of $_POST.

Otherwise, this method may return any results of deserializing
the request body content; as parsing returns structured content, the
potential types MUST be arrays or objects only. A null value indicates
the absence of body content.

[devanych]

https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-17-http-factory-meta.md#55-why-is-there-no-factory-for-creating-a-serverrequestinterface-from-superglobals