Update a list field in Gravity Forms

functions.php

// Update a List field in Gravity Forms
//Change the '6' at the end to the correct form id
add_action('gform_post_submission_6','update_list',10,2);
function update_list($entry, $form){
	$entry_id = $entry['id'];
	//print_r($entry);
	$list_values = array(
		array(
		'Column 1' => 'one',
		'Column 2' => 'two',
		'Column 3' => 'three',
		),
		array(
		'Column 1' => 'i',
		'Column 2' => 'ii',
		'Column 3' => 'iii',
		),
		array(
		'Column 1' => '1',
		'Column 2' => '2',
		'Column 3' => '3',
		),
	);
	$list_value = serialize( $list_values );
	//Change the '9' to the correct field id
	GFAPI::update_entry_field($entry_id,9,$list_value);
}