Adds additional metadata to the query.
Often, a query may need to provide additional contextual data to alter hooks. Alter hooks may then use that information to decide if and how to take action.
$key: The unique identifier for this piece of metadata. Must be a string that follows the same rules as any other PHP identifier.
$object: The additional data to add to the query. May be any valid PHP variable.
QueryAlterableInterface The called object.
Overrides QueryAlterableInterface::addMetaData
public function addMetaData($key, $object) {
$this->alterMetaData[$key] = $object;
return $this;
}