src/Http/Formatting/RequestParser.php
public function getClientIPAddress(IHttpRequestMessage $request): ?string
    {
        $clientIPAddress = null;
        $request->getProperties()->tryGet(self::CLIENT_IP_ADDRESS_PROPERTY, $clientIPAddress);

        return $clientIPAddress;
    }
public function getClientIPAddress(IHttpRequestMessage $request): ?string
    {
        $clientIPAddress = null;
        $request->getProperties()->tryGet(self::CLIENT_IP_ADDRESS_PROPERTY, $clientIPAddress);

        return $clientIPAddress;
    }
Gets the client IP address from the request

@param IHttpRequestMessage $request The request to look in
@return string|null The client IP address if one was found, otherwise null