Silverstripe non-associative array config

blah.php

<?php

	public function getRequiredFields() {
		$fields = self::config()->required_fields;
		//hack to allow overriding arrays in ss config
		if(self::$required_fields != $fields){
			foreach(self::$required_fields as $requirement){
				if(($key = array_search($requirement, $fields)) !== false) {
				    unset($fields[$key]);
				}
			}
		}
		$this->extend('updateRequiredFields', $fields);
		return $fields;
	}

Another solution could be to use a seperate array for overriding values

if($f = self::config()->custom_required_fields){
   $fields = $f;
}