system/classes/Collection.php
protected function generateContent()
    {
        $this->content = array_merge_recursive((array) $this->signature, (array) $this->singleton);
        $this->contentKeys = array_keys($this->content);
        $this->contentModified = false;
    }
protected function generateContent()
    {
        $this->content = array_merge_recursive((array) $this->signature, (array) $this->singleton);
        $this->contentKeys = array_keys($this->content);
        $this->contentModified = false;
    }
Merges the $signature and $singleton resources together into a single result stored in $content.

@return null