code: public function getPrefixMap() {
  		$prefixMap = (array) Configure::read('SimpleRbac.prefixMap');
  		if (empty($prefixMap) && $this->_config['allowEmptyPrefixMap'] === false) {
  			throw new \RuntimeException('SimpleRbac.prefixMap configuration is empty!');
  		}
  		return $prefixMap;
  	}
docs: Can be overriden if inherited with a method to fetch this from anywhere, a database for exaple
  
  @return array
  @throws \RuntimeException