Cache/RequestLastModifiedCache.php
public function onViewCreate(ContentfulViewEvent $e)
    {
        $viewMeta                           = $e->getView()->cfMeta;
        $updated                            = $viewMeta['updatedAt'];
        $this->itemIds[$viewMeta['itemId']] = true;
        if ($this->lastModifiedContent === null) {
            $this->lastModifiedContent = $updated;
        } else {
            if ($this->lastModifiedContent < $updated) {
                $this->lastModifiedContent = $updated;
            }
        }
    }
public function onViewCreate(ContentfulViewEvent $e)
    {
        $viewMeta                           = $e->getView()->cfMeta;
        $updated                            = $viewMeta['updatedAt'];
        $this->itemIds[$viewMeta['itemId']] = true;
        if ($this->lastModifiedContent === null) {
            $this->lastModifiedContent = $updated;
        } else {
            if ($this->lastModifiedContent < $updated) {
                $this->lastModifiedContent = $updated;
            }
        }
    }
Collect ViewEvents to build lastModified date.

@param ContentfulViewEvent $e