src/Grant/AbstractGrant.php
protected function getServerParameter($parameter, ServerRequestInterface $request, $default = null)
    {
        return isset($request->getServerParams()[$parameter]) ? $request->getServerParams()[$parameter] : $default;
    }
protected function getServerParameter($parameter, ServerRequestInterface $request, $default = null)
    {
        return isset($request->getServerParams()[$parameter]) ? $request->getServerParams()[$parameter] : $default;
    }
protected function getServerParameter ( $ parameter , ServerRequestInterface $ request , $ default = null ) { return isset ( $ request -> getServerParams ( ) [ $ parameter ] ) ? $ request -> getServerParams ( ) [ $ parameter ] : $ default ; }
Retrieve server parameter.

@param string                 $parameter
@param ServerRequestInterface $request
@param mixed                  $default

@return null|string
Retrieve server parameter .