Bridge dependencies on Bootstrap class/interface unclear

[andig]

I'm seeing problems trying to get my application up and running again on "naked" HttpKernelAdapter:

PHP Fatal error:  
Call to undefined method Volkszaehler\Util\Httpd\ReactInterface::getStaticDirectory() in /home/pi/volkszaehler.org/vendor/php-pm/httpkernel-adapter/Bridges/HttpKernel.php on line 61

This is what it comes down to:

• BridgeInterface apparently relies on BootstrapInterface but doesn't declare this dependency in the constructor https://github.com/php-pm/php-pm/blob/master/Bridges/BridgeInterface.php#L17. This dependency should be explicit?
• HttpKernel->getStaticDirectory relies on BootstrapInterface->getStaticDirectory which isn't part of the interface (https://github.com/php-pm/php-pm-httpkernel/blob/master/Bridges/HttpKernel.php#L59). We could either add getStaticDirectory to the BootstrapInterface but it feels kind of redundant and some applications may not need it (they could return empty- I'd prefer this approach). Alternatively add a second StaticContentInterface that a bridge can chose to implement or not- sounds a bit overkill?
• https://github.com/php-pm/php-pm-httpkernel/blob/master/Bridges/HttpKernel.php#L149 relies on BootstrapInterface->requestClass() which isn't part of the interface. An approach might again be for HttpKernel to use Symfony/HttpFoundation/Request as class unless Bootstrap implements RequestClassInterface which allows to return a more specific class. We could get rid of AbstractBootstrap then.

May sound a bit complex but would remove the hard and non-explicit dependencies. I'd be happy to draft a patch if the direction becomes clear/ gets buy-in.

[andig]

@marcj ok to merge the other one as well? Will only work if I get both ;)