Map::getFieldsBySource

private function getFieldsBySource($source)
{
	$fields = $this->find(
		array('=SOURCE' => $source),
		array('CONTAINER' => new Collection())
	);
	$names = array();
	/** @var Scalar $field */
	foreach($fields as $field)
	{
		$names[] = $field->getName();
	}

	return $names;
}