Request has invalid documentation or invalid constructor handling

[bradynpoulsen]

According to https://github.com/guzzle/psr7/blob/master/src/Request.php#L28-L29 the Request class can be created using

<?php
$request = new Request(null, null);

However, the UriInterface validation will cause that to throw an InvalidArgumentException. See https://github.com/guzzle/psr7/blob/master/src/Request.php#L43-L49

Looking at the PSR-7 definition for RequestInterface, neither getMethod or getUri may return anything but a string and UriInterface respectively. My gut feeling is that the documentation should then be considered invalid.