This package is deprecated because CSP support has been added to the nette/http package in version 2.4.4...
Nette/http package does have very similar syntax and additionally it support nonces. Here is the future syntax:
http: csp: default-src: "'self' https://example.com" upgrade-insecure-requests: script-src: 'nonce' style-src: - self - https://example.com
Yeah that's right - you don't have to register special extension, because it's already in Nette Framework. Please read more about nonce support in Nette Framework forum.