private function compileHeaders(): array
    {
        return array_merge(
            $this->security['settings']['enable-hsts'] ? $this->hsts() : [],
            $this->security['settings']['enable-hpkp'] ? $this->hpkp() : [],
            $this->security['settings']['enable-ect'] ? $this->ect() : [],
            $this->security['settings']['enable-extras'] ? $this->extras() : []
        );
    }