api/MarkLogic/MLPHP/Metadata.php
public function addCollections($collections)
    {
        if (is_array($collections)) {
            $this->collections = array_merge($this->collections, $collections);
        } else {
            $this->collections[] = (string)$collections;
        }
        return $this;
    }
public function addCollections($collections)
    {
        if (is_array($collections)) {
            $this->collections = array_merge($this->collections, $collections);
        } else {
            $this->collections[] = (string)$collections;
        }
        return $this;
    }
Add collections metadata.

@param array|string $collections An array of collection strings or a collection string.
@return Metadata $this