Gravity Forms - Pre-Populate List Field

functions.php

<?php

/* Change form ID */
$location_form_id = 9;

add_filter( 'gform_pre_render_'.$location_form_id, 'populate_list' );
add_filter( 'gform_pre_validation_'.$location_form_id, 'populate_list' );
add_filter( 'gform_pre_submission_'.$location_form_id, 'populate_list' );
add_filter( 'gform_admin_pre_render_'.$location_form_id, 'populate_list' );
function populate_list( $form ) {
    foreach ( $form['fields'] as &$field ) {
		if ( $field->label =='Add Field Label Here'){
			$list_insertions[] = array('custom column name 1'=>'Column 1 Entry','custom column name 2'=>'Column 2 Entry');
		}
 		$field->defaultValue = $list_insertions;
    }
	return $form;
}